Awesome, I'll be going to the pawn shop tommorrow.
Nice. But, also make sure the plugs are the right ones built for the dreamcast. One guy on craigslist was just selling a dreamcast with generic AV cables that didn't even fit into the dreamcast plug.

Make sure the end of the power cord that plugs into the Dreamcast looks like one of those.

Make sure the end of the AV cord that plugs into the Dreamcast looks like this one.