You might PM Leeindy -- he builds 'em, he might have some ideas. I sell them, but for the life of me, all of the major (and many of the minor) mfgrs are pretty much the same and I really don't see any significant differences.
I agree with gunrnr, most of the guns are forged in the same 3 or 4 places and they put whatever manufactuors name on it that is buying it. If I am not mistaken, Colt, Armalite, and Bushmaster are the only 3 that make their own lowers, but I could be wrong about that. Seems I remember reading that in The Gun Digest Book of the AR, but as I am at work right now, I can't verify that.
Another idea would be to take a lower and either have it blued or do a Durakote finish on it. If you're interested I will get you names of folks who have done good work for me or have otherwise been highly recommended by colleagues.
These guys have done about four pieces for me personally, plus I have sent them work from several of my customers. The guy who ran to company for many yrs retired and sold it, but I understand that the fellow who bought it is a long-time employee and does the same quality work.
Here's another outfit that does good Duracote work, according to reviews on another forum: http://www.ccr-refinishing.com
Either way, please let us know how it turns out and how you are treated by whomever you choose to do the work.