Actually the 7900 is pretty close in price to the 8600 seems like they go for like $115-160 on newegg these days, and the 8600 is in the 100-115 range. But honestly, $100 for a dx10 card? Not really what i'de consider all that crappy.
@ Andreas - Apparently the Xbox controller does not work inherently in SMB on Mac: http://www.supermeatboy.com/115/Things_every_Mac_user_should_know___/#b