I own 3 CMMG lowers and have built up 2 of them. I find that their quality is on par with everyone else. I would consider them a Tier 2 lower, with Noveske, POF, LWRC (and a few others) as Tier 1.
The brand of parts kit might change the price, but not really the value. A few other considerations: what type of buttstock? If adjustable, is it a mil-spec or commercial buffer tube?
I can't really put a price on it since I am stuck in CA and all firearms prices out here are inflated.