One company y'all should consider is Olympic Arms. I use Olympic Receivers and build the rifles with Bushmaster and Colt parts. I guess I like Oly receivers because a stripped lower is only $99, they are mil-spec, and I can get custom serial numbers done. Maybe I just like the lion on them better than the snake, but I have never had a problem.
Also I like mil-spec parts. 5 non-colt rifles, all interchangeable parts. Should I throw a colt in to the mix I'd probably have to get extra spare parts for trigger and pivot pins, or adapters to use different upper receivers. Also I might not could have any of my 2 stage match triggers in them. No colts means I have no sear blocks, and with Olympic I don't even have hammers with that silly little notch in them. All Bushy and most Colt's I've seen both have them.
Now I'm not knocking colts, just their attempts to create a "you should only be able to get parts from us at our price" situation. I will buy the mil-spec parts, carry handle sights, M4 handguards, barrels etc. from Colt, but only when I find good deals on them. Some folks see the word colt on a product and think they can charge you twice as much for it, and that's wrong too.
4 of my 5 are Oly's (at least the lowers are). Anybody bought a complete rifle from them? IMHO they should be included in the "affordable yet quality" category if the rest is as good as the lowers.