I dunno. For the price they are getting for the military receivers ($150+) adding a barrel ($200+) and all the misc parts, you'd end up paying about the same as a working, complete rifle. Doesn't look very attractive to me. With Carbines running about $700 in nice shape, I think it would be difficult to build one for much less.
Also interesting is the fact that the commercial receivers are included. Weird.
Rome