Get a larue tactical complete upper for $750. Then get any lower and drop in a larue 2 stage trigger. For a grand you have a premium rifle.

I just did this and used an Aero M4E1 stripped lower with BCM parts kit, LaRue 2 stage trigger. It's real nice and I'd put it up against any Gucci AR out there. Total price about $1,050.

Enjoy!