SB StartupBasket
All ideas
75 /100 GO Medium complexity

CostProof — sourcing-cost defender for Amazon sellers

Turns your supplier invoices into per-SKU sourcing-cost evidence Amazon accepts — so lost-inventory payouts hit true cost, not Amazon's lowball.

Retail SaaS Global AI-agentSMBe-commerceWorkflow-automationSolo-builder
— views
Evaluation Scores
75/100

GO

Overall Score

16
Problem
13
Demand
12
Build
12
Distrib.
11
Revenue
8
Time
3
Defense

CostProof — sourcing-cost defender for Amazon private-label sellers

1. One-liner

Turns your supplier invoices into per-SKU sourcing-cost evidence Amazon accepts — so lost-inventory payouts hit true cost, not Amazon’s lowball estimate.

2. Trend signal — why now?

On March 10–31, 2025, Amazon flipped its FBA inventory-reimbursement policy: lost/damaged inventory is now reimbursed at manufacturing (sourcing) cost, not selling price. For a $50 item that costs $15 to source, the payout dropped ~70%. Amazon estimates your sourcing cost unless you submit proof — and sellers report the estimates run roughly half of actual cost (one verbatim forum case: Amazon estimated $20.37 against a real $53 manufacturing cost).

The kicker: when sellers try to correct the estimate, Amazon rejects the re-evaluation — forum threads titled “Sourcing Cost is SO Broken” and “Amazon denying my sourcing cost Re-Evaluation, what can I do?” show denials even for requests of “$1 more than the estimated sourcing cost.” Amazon’s accepted proof has rigid field requirements (document name, invoice number, buyer entity + address + VAT, SKU, quantity, unit price, currency) and accepts messy formats like Chinese Fapiao. In January 2026 Amazon began rolling out a bulk sourcing-cost upload — confirming this is now an active, supported workflow sellers must operate, not a fringe edge case.

Meanwhile the recovery-tool market is consolidating upmarket: Carbon6 sold to SPS Commerce for $210M (2025), pulling the category toward enterprise brands and deduction-management — leaving the long-tail private-label seller to fight the sourcing-cost estimate alone.

Provenance:

3. The opportunity

Every existing recovery tool (GETIDA, Carbon6/Seller Investigators, Shopkeeper, Refunzo) is a claim-filing engine: it finds discrepancies in your FBA ledger and files for reimbursement, taking 12–25% of what’s recovered. None of them solve the new bottleneck the March-2025 policy created: the per-unit value Amazon pays out. They recover the claim; Amazon then pays it at its own lowballed sourcing-cost estimate. The seller still loses 40–60% on every lost unit because the COGS evidence on file is Amazon’s guess, not the seller’s real invoice.

That’s the gap. CostProof isn’t a competing recovery tool — it’s the evidence layer underneath all of them. It ingests the seller’s actual supplier invoices (PDFs, photos, Fapiao, packing lists), extracts the per-SKU unit cost, maps it to ASIN/FNSKU, formats it into Amazon’s exact accepted-proof schema, bulk-submits via the new sourcing-cost portal, and — critically — drafts the rebuttal when Amazon rejects the re-evaluation. Every reimbursement after that, whether the seller files it themselves or via GETIDA, pays out at true cost.

Incumbents won’t build this well because (a) their commission model rewards more claims, not higher per-claim value, and (b) the consolidators are chasing enterprise deduction-management, not a $39/mo private-label seller drowning in WeChat invoice screenshots.

4. Target market

  • Primary customer: Amazon private-label / wholesale FBA sellers doing $200K–$5M/yr GMV, 50–800 active SKUs, 1–3 person teams, sourcing from China/Vietnam/India. Owner-operator or their ops VA.
  • Why they buy: “Amazon lost 40 of my units and reimbursed me $814 instead of $2,100 because their sourcing-cost estimate is half what I actually pay — and when I tried to fix it they rejected me.” It’s recurring, it’s bleeding margin every month, and the fix is tedious-but-tractable paperwork they hate doing.
  • Rough TAM reasoning: ~2M+ active Amazon sellers; ~54–67% run private label, the segment that owns supplier invoices and has real COGS to prove. Conservatively 300K–500K sellers have enough SKUs + lost-inventory volume to feel this monthly. We need ~2,000 paying to hit $1M ARR.
  • Why now for them: The policy is barely a year old, the bulk-upload portal just opened (Jan 2026), and sellers are actively hitting rejections this quarter. The pain is fresh and unsolved — not a someday problem.

5. Product sketch (MVP)

  • Invoice drop-zone: upload/forward supplier invoices, Fapiao, packing lists (PDF, image, even WeChat screenshots); AI extracts unit cost, quantity, supplier, SKU.
  • SKU↔ASIN↔FNSKU mapper: reconciles supplier line-items to the seller’s Amazon catalog (pulled via SP-API), flags unmatched SKUs.
  • Amazon-schema formatter: outputs each sourcing cost in Amazon’s exact accepted-proof field structure (document name, invoice no., buyer entity/VAT, SKU, qty, unit price, currency) so it passes validation first try.
  • Bulk submitter: pushes the whole catalog’s sourcing costs through Amazon’s bulk upload — no per-ASIN clicking across 500 SKUs.
  • Rejection rebuttal drafter: when Amazon denies a re-evaluation, generates the appeal with the correct invoice citations and policy language.
  • Underpayment watcher: monitors reimbursements; flags any payout where Amazon used an estimate below your documented cost, with the dollar delta.
  • Audit binder export: per-SKU evidence pack (invoice + extracted fields + submission receipt) for the seller’s records.

6. AI angle — what’s load-bearing

Remove the AI and this is a data-entry sweatshop. The load-bearing work is document understanding on genuinely messy inputs: Chinese Fapiao in mixed CJK + English, photographed invoices, multi-currency packing lists, line-items that don’t name the Amazon SKU. A 2026 vision-language model reads these, normalizes to per-unit cost, and maps fuzzy supplier descriptions to the seller’s ASIN catalog. The second AI surface is the rebuttal drafter — reading Amazon’s rejection reason and composing the policy-grounded appeal. Both are exactly the “collapse a 2-hour task into 2 minutes” shape: a seller with 400 SKUs and a folder of 80 supplier invoices goes from a multi-day spreadsheet slog to a reviewed bulk submission in under an hour.

7. Localization angle (if any)

Not a geography play, but a supplier-origin one: the hardest invoices are Chinese (Fapiao) and increasingly Vietnamese/Indian as sourcing diversifies. First-class Fapiao parsing is the technical moat-let — generic invoice OCR chokes on it. Sellers themselves are global (US/EU/UK marketplaces) so the product is English-UI, multi-currency, sells worldwide. No payment-rail localization needed (Stripe, seller cards).

8. Business model — path to $1M–$5M ARR

  • Pricing: Flat SaaS, not commission (the differentiator vs GETIDA’s 25% cut). Starter $39/mo (up to 100 SKUs), Growth $99/mo (up to 500 SKUs + rejection rebuttals + underpayment watcher), Pro $249/mo (unlimited SKUs, multi-marketplace, VA seats). Plus a $149 one-shot “Sourcing-Cost Catalog Audit” for sellers who just want their whole catalog documented once before the next loss.
  • ACV: ~$600 blended (mix skews Growth).
  • Math to $1M ARR: ~1,700 sellers × $600 = $1.02M. At 300K addressable, that’s 0.6% penetration — not heroic.
  • Math to $5M ARR: ~8,300 sellers × $600, or hold seller count and grow ACV via Pro/multi-marketplace + a per-recovered-dollar upsell. Would need an agency/aggregator reseller channel (people who manage 50–200 seller accounts).
  • Expansion path: SKU-tier upgrades as catalogs grow; add a thin recovery-filing module later (optional, flat-fee, not commission) to capture the full workflow; white-label tier for Amazon agencies and VAs.

9. Go-to-market wedge — first 100 customers

  • Seller-Central forum + subreddit ambush: the exact threads cited above (“Sourcing Cost is SO Broken”, r/FulfillmentByAmazon, r/AmazonSeller) are full of sellers describing this pain this month. Reply with a Loom showing their $20.37-vs-$53 problem fixed in two minutes; DM the OPs. ~100 warm, self-identified targets already posted.
  • Free “Sourcing-Cost Gap” scanner: connect SP-API read-only, show “Amazon’s estimates are underpaying you $X across N SKUs” — a hard dollar number. Free audit → paid fix. This is the same wedge GETIDA used (free audit) but on the value side.
  • Amazon-agency / VA partnerships: 50–200-account agencies feel this across their whole book. White-label or rev-share; one agency = dozens of seats.
  • YouTube/podcast FBA creators: the FBA-education ecosystem (Helium 10 / Jungle Scout adjacent creators) makes content on every policy change; a clean “here’s how to stop Amazon lowballing your COGS” sponsorship/affiliate fits their audience precisely.

10. Build complexity — justification

Medium. Off-the-shelf: SP-API for catalog + reimbursement/inventory reports, a 2026 vision-LLM for invoice/Fapiao extraction, standard web stack, Stripe. Custom work is the SKU↔ASIN reconciliation (fuzzy matching supplier line-items to the seller catalog) and the Amazon-schema validator + bulk-submission flow, which must track Amazon’s evolving accepted-proof spec. SP-API approval (PII/restricted roles) adds onboarding friction but no custom infra. A 2-person team ships a credible v1 in 10–14 weeks.

11. Gating checklist

GatePass?Note
Legal in target market✅Seller submits their own genuine invoices; we format/transmit on their behalf. No circumvention.
Ethical — no harm / dark patterns✅Helps sellers claim true costs they’re owed; no inflation of figures (that’s fraud — explicitly disallowed).
Market exists (evidence above)✅Active forum complaints, 30+ paid recovery tools, $210M Carbon6 exit.
1–5 person team can build this✅2 people, ~10–14 weeks.
Launchable with <$50K / ₹40L✅Inference + SP-API + hosting; <$15K to launch.

12. Feasibility score

AxisWeightScoreNotes
Problem intensity2016/20Bleeds margin monthly, sellers actively angry and searching — but it’s a slow bleed, not hair-on-fire-this-second for every seller.
Demand evidence1513/15Verbatim forum complaints, huge paid-adjacent market, fresh policy. Direct demand for this specific evidence-layer cut is inferred, not yet proven.
Build feasibility1512/15SP-API + vision extraction is tractable; Fapiao parsing + schema-tracking are the real work.
Distribution clarity1512/15Self-identified targets in known threads + free-scanner wedge + agency channel. Conversion math still a guess.
Revenue mechanics1511/15Flat SaaS is clean and defensible vs commission, but $39–249 ACV needs volume; some sellers will balk at paying when “Amazon should just fix it.”
Time to first revenue108/10Free-scanner-to-paid + pre-sellable audit; first dollars in 4–8 weeks of launch.
Defensibility103/10Thin. Incumbents could bolt this on; moat is Fapiao-parsing quality, agency relationships, and being the flat-fee anti-commission brand.
Total10075/100

13. Qualitative modifiers

Founder-fit tags

technical-heavy (SP-API + document AI + reconciliation), domain-expertise-required (must live inside Amazon reimbursement policy and update with it).

Key assumptions to validate (3–5)

  1. Assumption: Sellers will pay flat SaaS for evidence prep even though recovery tools “feel free” (commission-only). How to test: Show 30 sellers the free-scanner dollar-gap, then price-test $39/$99 — measure % who convert vs say “I’ll just do it myself.”
  2. Assumption: AI can extract Fapiao/messy invoices accurately enough that Amazon accepts the submission first-try ≥80%. How to test: Run 50 real seller invoices through extraction → Amazon validation; measure acceptance rate.
  3. Assumption: Amazon won’t make this trivial by auto-honoring uploaded invoices (collapsing the rejection pain). How to test: Track re-evaluation rejection rate in forums over 60 days; if rejections drop to near-zero, the rebuttal value evaporates.
  4. Assumption: The free SP-API gap-scanner converts at ≥5% to paid. How to test: Ship scanner-only landing page to 500 forum/subreddit visitors, measure signup→paid.

Risk flags

  1. Platform dependency: Entirely Amazon-policy-bound. If Amazon fixes the estimate accuracy, raises payouts, or auto-accepts invoices, the wedge shrinks. Mitigate by owning the broader COGS-evidence + reimbursement workflow, not just the rejection gap.
  2. Incumbent bolt-on: GETIDA/SPS-Carbon6 could add sourcing-cost evidence to their suite. Our edge is flat-fee positioning + Fapiao quality + the long-tail they’re abandoning.
  3. Market timing: Could be slightly early if most sellers haven’t yet felt a big loss under the new policy — or slightly late if Amazon’s bulk tool gets good. The 12-month window post-policy is the sweet spot; move fast.
  4. SP-API gatekeeping: Restricted-data role approval can stall onboarding; design a no-API manual-upload path so value isn’t blocked on Amazon’s approval queue.

14. Structured verdict

Score:                  75/100
Verdict:                GO
Confidence:             Medium
Best-fit builder:       Technical founder who's run an FBA account (or has an FBA-seller co-founder/advisor); document-AI comfort.
Time to revenue:        4–8 weeks post-launch (free-scanner → paid; pre-sellable catalog audit)
Capital to launch:      $10–15K
Top 3 assumptions to validate first:
  1. Flat-fee willingness vs "free" commission tools — price-test 30 sellers off the free gap-scanner
  2. First-try Amazon acceptance ≥80% on real Fapiao/messy invoices — run 50 through extraction→validation
  3. Free-scanner → paid conversion ≥5% — ship scanner landing page to 500 targeted visitors
Kill criteria:
  - Abandon if <5 of 50 sellers shown a real dollar-gap convert to paid within 4 weeks
  - Abandon if Amazon ships invoice auto-acceptance or accurate auto-estimates that drop forum rejection rate to near-zero
  - Abandon if first-try Amazon validation acceptance stays below 60% (product can't deliver its core promise)

15. Next step — 1-week validation sprint

  • Day 1–2: Build the free “Sourcing-Cost Gap” mock: take 5 real sellers’ SP-API reimbursement exports (or screenshots from forum posters), hand-compute Amazon-estimate-vs-actual-cost delta, show each their dollar number.
  • Day 3–4: DM the 100+ self-identified sufferers in the cited Seller-Central / Reddit threads with a 90-second Loom of the gap + the fix. Offer the $149 one-shot catalog audit as a pre-sell.
  • Day 5: Decide go/no-go. Falsifiable bar: ≥10 sellers reply engaged AND ≥5 pre-pay the $149 audit (or commit to a paid pilot). Below that, the pain isn’t worth flat money to them — kill or re-shape.

Interested in a detailed proposal?

Get a deep-dive with market research, competitive analysis, and implementation roadmap.

Contact us

info@startupbasket.ai