Dreamcast you say? Well well, My store has plenty, I wish I could easily sell you one.
I'd recommend Sonic Adventure 1 and 2 by far. Skies of Arcadia, Grandia II, Shenmue, Seaman, Spike Cannon, Resident Evil Code Veronica, and any other game made by Capcom for the Dreamcast was always sweet. It just sucks that the most popular games, fighters, are always the high dollar ones.