Where is the best place to get aged beef in Austin?
OK, I'll bite. I assume you mean dry aged as opposed to wet aged. There is no "best place". Several places sell a couple cuts - mostly strip and ribeye (CM, Hole Foods, upscale HEB's in cryovac), but no one place outshines any other except in price.
At one time Hole Foods downtown had a room dedicated to it, but I'm not so sure that still exists anymore. The prices were astronomical - not that many Hole Foods shoppers are wise to prices.