Don't know if anyone is still reading this thread. New member (here), just moved to SC.
Stay away from Rock River, DPMS, etc. You'll be sorry in the long run. Spring a few more $ for mil-spec grade parts.
G&R Tactical - owned and run by the guy that runs M4carbine.net has a deal and a half:
http://www.gandrtactical.com/cgi-bin/co ... esult.html
Go with the ALG ACT (advanced combat trigger) - the best for the money drop-in single stage trigger. Made by Geissele (best in the business) but the company is owned by his wife for unknown reasons. $119 with trigger. Alas, out of stock right now though.
Good luck with the build. Incidentally, I've got a lightly used LMT 2-stage trigger I'll sell you if you want, PM me if interested.