I'm really shocked no one has mentioned our good buddy Tony at IRO. They have a pretty nice aluminum track bike, available complete from $574.00, or as a frame and fork for $259.99. The geometry isn't as steep as some track bikes, but the frames are nice and IRO is one of the best companies you could ever hope to deal with. There's a fair number of IROs over at fixed gear gallery.

http://www.irocycle.com/id77.html