Yeah, like Nyyankeesfan28 pointed out, Beckett only shows MLB-licensed cards (which is probably 99.99% overall). There are various odd-ball, MiLB, and other non-MLB cards out there that won't show up on Beckett, but it's as good as you'll ever find. I'm guessing most people accept the Beckett number as the end-all.
Always looking for Verlander, Cabrera, Maybin, Mike Stanton (marlins), and Avisail Garcia.
*TRYING TO COMPLETE MY VERLANDER ROOKIE COLLECTION. 44/47. ONLY 3 TO GO!*