A bit late jumping here, but I work in a used bookstore that also sells games, consoles, dvds, and electronics. We essentially function as a pawn shop with a trade credit system. I work in the gaming/electronics department and we poach gamestop's pricing for what they carry and use a combination of digital press, amazon, and ebay to find our selling prices. Standard payouts are 1/2 trade, 1/4 cash for things we don't care much about, and around 3/5 trade 1/2 cash for things that we really want and know will sell. Nothing is fixed, the employees buying are allowed to use their own discretion. We discount most things 10% if you're nice to us, %20 if you're an educator.
The result? A huge community of loyal customers who benefit from our business model. Not because our prices are necessarily great compared to what you can find online, but because you can get rid of a wide variety of media you aren't using and apply that towards things you want, finding things that aren't available anywhere else. We're also the only source in the region for collectible old school consoles and their games. It sucks to give someone $80 for a 360, but the ones that get $30 for a working NES, or $50 for a Master System with all the trimmings are happy. I would much rather be keeping these things circulating than have them end up in a dumpster. Our product diversity separates us from gamestop, but I don't see their general model as being necessarily evil.