I have a Bushmaster and a Bushmaster/Spike's Tactical, and they both work great. A friend of mine has a Stag, and it also seems to be good quality.
On the other hand, I've had some trouble with an Olympic Arms AR I shot....Not saying they're a bad brand, but the one I shot had some issues...
As for the price, I believe the Bushy was around $1000 new five years ago, and I pieced together my second gun for ~ $750.
Good luck.