I personally just picked up a set of 17x7 OZ Superleggeras (previous model from the current Ultraleggeras) for barely over $500. 15.5lbs per wheel with Bridgestone RE11As mounted on them (tires weren't included of course). The RE11s are amazing and I use them for daily driving, autocross, and track days, but if you only do occasional autocross I would recommend a tire that is one step down as another member mentioned.
Possible options include the Hankook V12s, Continental Extreme Contact DWs, and Michelin Pilot Super Sports.
http://www.ft86club.com/forums/showthread.php?t=62401