DSG is selling the Colt 6721, 6920, and 6720 for $879, $899, and $975, respectively:
http://dsgarms.com/coar6721
http://dsgarms.com/co6920
http://dsgarms.com/coar6720
I've seen other vendors putting them on sale, and Walmart sells them (although not in my area).
I had a factory-built Stag and currently have a self-built one. I also have a Colt. The Stags are nice; the Colt is nicer. At the above prices, you can't go wrong.
Another option is to buy a complete upper and complete lower as separate pieces and mate them together when you get them. You'll save $$ because the federal excise tax is based on the value of the lower plus whatever is attached to it. Complete Colt and Stag uppers are available. Get one of those and mate it to a PSA complete lower ($159 for the standard version).
Colt upper:
http://www.gandrtactical.com/cgi-bin...n&key=LE6920CK