I have the Aero Precision lower and upper which cost 75 each. They are high quality and the fit and finish is perfect. I wouldn't spend more than $100 on a lower because they all pretty much do the same thing. You might want to put your money on the more important parts like the bcg, barrel, etc.
Ordered a PSA lower yesterday and trigger group. I will have a trusted gunsmith polish up the trigger so it breaks a little more smoothly. I have decided I will be using a BCM upper reciever with m4 feed ramps, and their BCG. Still on the fence for what barrel to I want. I can't decide between a plain old 16" carbine or 20" rifle length barrel. Kinda kickin around the idea of a 20" in .300blk out or .450 bushmaster. Idk what to do yet