Several very well known gunsmiths have been mentioned in this thread so far, you wouldn't go wrong with any of them to be honest. There are several more out there that are also worth looking into.
Since you are in Az, I brought up PCR and as Reaper mentioned, some places get backlogged and or QC drops. So whom ever you decide to go with, be sure to ask about build times.
Another gunsmith that has built a gun for me that I'd highly recommend is Marc/ Spartan Precision Rifles (
http://www.spartanrifles.com )