If you follow the "Hot Deals" forum here, I believe you can get one in the US for $79.95.
Seeing as Sega is clearing out their inventory, I can't see it being much cheaper over there, save Japan, where the Dreamcast wasn't/isn't selling well.
I own a Dreamcast (bought on release date 9/9/99) and I wouldn't trade it for the world. I just wish they had SSX for it, it's the best game I have played in a LONG time!