Every price says where it came from
Each result carries the name of the source that answered it. A number with no provenance is a number you cannot defend to a buyer, so there is no such thing here as an unattributed price.
Someone holds up something you did not plan to sell and asks what you would take for it. You have about four seconds before the silence gets awkward. Product Finder is built for those four seconds: one search box, real prices from the markets that know the item, and a label on every result telling you which market produced the number.
Amazon, eBay, TCGplayer and PriceCharting are queried together. Amazon is covered twice over, through Keepa and through Amazon’s own Product Advertising API, so a gap at one does not leave you with nothing.
Each result carries the name of the source that answered it. A number with no provenance is a number you cannot defend to a buyer, so there is no such thing here as an unattributed price.
Trading cards ask the card market first, retro games ask the game market first, and general goods start with the big catalogues. You pick the category; the order behind it is already set.
UPC, ASIN, ISBN, FNSKU, LPN, or just a search phrase. The box works out what you gave it instead of making you pick a mode first.
No barcode, and no name you trust? Send a photo and let the identification step turn it into something searchable.
Amazon results expand into full detail with identifiers and pricing, so you can judge a number rather than just read it.
Everything you have resolved, searched, aired or displayed, kept as a scrollable list on your account. The thing you looked up last Tuesday is still there this Tuesday.
Results are cached for a day, so the second person asking about the same item does not cost you another round trip.
A rolling 30 day view of your Amazon data usage, next to the share of it the cache saved you. It is a usage readout, not a countdown to being cut off.