Radeon 9200 for $80. I got mine (actually a 9000 for $89 last July)from Thompson's Computer Warehouse[1] (http://www.tcwo.com/cgi-bin/webc.cgi/st_prod.html?p_prodid=2396&sid=44oBmP0@qJxQ0Dm).The 9200 is supported extremely well with XFree86 4.3 (currently in experimental) and the open source DRI drivers.
Does video playback work "out-of-the box"? Obviously I'd need some app to play them, but other than that, would it run right away?
I have the ATI Radeon 8500DV (it's DV, because of TV Support), which asked me to get new drivers, DRI, or many others (can't remember them right now).