I'm a solo dev who spent the last 6 months building a sports card scanner app from scratch. Along the way I hit an interesting problem: every existing scanner on the market gives different prices for the same card, and almost none of them tell you why.

So I scanned the same 2018 Topps Update Shohei Ohtani rookie card on 5 different pricing apps. The results:

CollX: $87

Ludex: $74

Card Ladder: $91