Isn't this a dying market? I've noticed a lot of new cars whose radio doesn't look upgradable - and the ones that are (and are new) would probably look ugly with an aftermarket in. I just want a damn aux port.Try GM products? I can't think of any olderish ones that aren't 2din.
Honestly I'd say wait until your budget can be $250. A used PS3 + larger hdd could probably be had for $150-200.
Also, the 775 build posted a few above has a CPU that does not come with a sink or fan ($9 option). Also, it's a 775 build.