I just got done putting mine together. I got a RRA LAR-15 complete lower for $300, and an Armalite 20" upper with 1/7 twist barrel for $550, both brand new. With all the extras, I'm into it $2100-$2200. But, the complete rifle, just upper and lower, cost me $850 for a fully functioning rifle. I got the setup I wanted, and saved money by buying the upper and lower separately.
I never really buy complete rifles, because I know that I can get a quality lower and a quality upper, put them together, and have a perfectly functioning rifle. All the while saving a couple hundred bucks.
Here is a pic of my latest rifle-