Out of all of the games you have what have to be the games that are hard to find nowadays and even if you did find them at a store or online they'd cost an arm and a leg?
Well I have all three Street Fighter 3s on Dreamcast, you can't find the DC versions of those anywhere, even when the games came out, I did get SF3: Double Impact from Ansem foor a Yugioh card (A decent one too)
I also have Record of Lodoss War fro DC, that game is probably the Suikoden 2 of Dreamcast. I got that game when I traded my N64 and afew games for it and Ecco the Dolphin.