Evidence provenance and comparison
Flipper keeps four kinds of economic information visibly separate:
| Kind | Example | Meaning |
|---|---|---|
| Source fact | eBay asking price | Returned by a named external API for the current listing. |
| Estimate | Expected resale entered during analysis | A temporary user assumption, not an observed sale. |
| Derived value | Expected net profit | A Flipper calculation over named facts and estimates. |
| Actual historical fact | Acquisition cost or sale proceeds | A durable fact recorded after an event. |
Provenance answers where a value came from. Confidence answers how strong the evidence is. A value can have clear provenance and weak or unknown confidence.
Derived economics
- Landed cost uses asking price, tax, inbound shipping, travel, and other acquisition cost.
- Expected net proceeds uses expected resale less selling fees, outbound shipping, and other costs.
- Expected net profit uses expected net proceeds less landed cost.
- ROI uses expected net profit and landed cost.
- Profit velocity uses expected net profit and the supplied time-to-sale range.
Unknown inputs remain unknown. Native currencies are never compared or combined as equivalent.
Comparison workspace
Search results can select two to four opportunities for /deals/compare. Flipper sends only
bounded source identifiers, re-fetches each listing from eBay, and applies independently named
temporary assumptions to each deal. Submitted economics cannot overwrite an eBay source fact. The
workspace creates no deal-history, inventory, or accounting rows.
On narrow screens, comparisons stack as complete cards. Pairwise results list dimensions favoring each opportunity. A non-dominated (Pareto) opportunity is not worse on available comparable dimensions; it is not a winner, score, grade, or buy recommendation.
Sold-market evidence
As reviewed in September 2026:
- Browse API returns purchasable listings, not a generalized completed-sales dataset.
- eBay describes Marketplace Insights as its sales-history API, but the marketplace support page says it is restricted and not open to new users.
- Production Buy access requires approval and agreements under the Buy API requirements.
- Seller Fulfillment and local sales cover the connected seller's own history, not market-wide comps.
- A future user-provided export would need a defined schema, rights, provenance, and validation. Scraping sold/completed pages is not a fallback.
No realistically available official sold-data source currently passes the implementation gate.
Sold counts, sell-through, historical median prices, and market time-to-sale remain unavailable.
The Deals Sold comparables mode therefore states this limitation and performs no marketplace call.
GetMyeBaySelling sold rows and Sell Fulfillment orders are scoped to the authenticated seller;
they are not substituted for marketplace-wide comparable search. A listing ending, disappearing,
or moving to an unsold list does not establish that it sold or reveal realized proceeds.
Flipper's inventory, valuations, lifecycle timestamps, sales, and reconciled costs are promising future evidence. Later work needs comparable attributes, complete lifecycle windows, sample-size disclosure, and currency compatibility before learning from those records.
User-provided comparable evidence can now accompany each ephemeral opportunity. Sold and active asking summaries remain separate and currency-specific. They do not enter Pareto ranking, expected resale, liquidity, or confidence automatically.