How our value estimates work
Every number on this site traces to recent completed sales. Here's the exact method, and the limits you should know about.
Data sources
- Realized prices: recent eBay sold listings per category — completed transactions, typically ~100 per category per query, pulled via API and refreshed regularly. Never asking prices, never active listings.
- Singer serial records: factory allotment tables compiled by the International Sewing Machine Collectors' Society (ISMACS) — 9,200+ recorded allotments, 1851–1970s.
How we turn sales into a range
- We drop multi-item lots, so one sale = one item.
- We bucket by category and variant, and split by condition signals in the listing (original / restored / as-is).
- We report the 25th–75th percentile as the “typical range” and the median as the headline. Half of real sales land inside that range; we'd rather under-promise than quote you the one outlier.
- Cells with too few sales are flagged as thin data, not presented as solid ranges.
Seller's-net honesty
A market price is not what you pocket. We state both: selling on eBay nets roughly 85% after fees; selling to a dealer typically brings about half of retail, because the dealer carries the risk, the booth rent and the wait. Neither is a rip-off — they're different services.
What this is not
These are market estimates, not appraisals. For insurance scheduling, estate division or donation deductions, hire a certified appraiser who examines your item in person. And if you've read that an item like yours is “worth millions” — that number is almost always an asking price, a misread auction story, or fiction. We calibrate only on what buyers actually paid.
Known limits
- eBay skews toward shippable items; furniture and other heavy categories sell disproportionately local, so our ranges there lean conservative.
- Condition detection reads the seller's own wording, which is imperfect.
- Regional and seasonal swings are real; our ranges are national and recent, not local and today.