What's a good app for figuring out what my old baseball cards are worth without having to lug 'em down to the card shop?

Alright, so I downloaded LUDEX 'cause I got a shoebox full of old baseball cards collecting dust in the attic. Figured I'd see if any of 'em were worth more than the cardboard they're printed on. This app, LUDEX, it's pretty straightforward. You just point your phone's camera at the card, and it scans it, then tells you what it's going for. The interface ain't pretty, but it gets the job done. I wouldn't say it's 'built like a brick house', but it hasn't crashed on me yet, even after accidentally dropping my phone while using it on the tailgate. The value seems about right, compared to what I've seen online. Now, the battery drain is a killer – eats through my phone's juice faster than a rookie downs energy drinks. But hey, at least I know that '87 Topps McGwire is worth a few bucks. Beats guessing, right?