Thats a tough call right now. Because of the fear that Obama might pass a permanent AWB, AR-15 prices have gone through the roof. Expect to pay 50-100% more for one right now if you can get it.

Armalite, Bushmaster, DPMS, Colt, LMT,Les Baer, Charles Daly, Smith and Wesson, Rock River Arms, and Stag all make good rifles and carbines right out of the box. Their prices will vary from $800-2500+ depending on features and brand.