Stag Arms have a new 6.8mm hunting AR-15 called the Model 7 (Hunter).
The rifle features a 20.77″ 1:11 twist barrel, 2 stage match trigger, 5 round magazine and a Hogue pistol grip. Stag Arms has the price listed as $1,055.
Although I have not read an evaluation of hunting performance for commercially available 6.8mm SPC, the round produces similar energy to the .30-30 at the muzzle and offers significantly better downrange performance than the .30-30 or 7.62x39mm. Whitetail deer should be no problem.
More info @ Stag Arms