Brownells and Schuyler Arms are dumping Aero Precision lowers for $50 or less. I've bought and built so many of them, and I've yet to find one that is out-of-spec. I've been getting some very nice results from the Aero's coupled with the Aero/Ballistic Advantage barrels. One of my local gun stores sells Anderson Lowers for $30, but I'm not sold on them yet. I've also bought the Palmetto blemished lower receiver groups for $129 and I can't find the blems, unless it's the small marks inside the magazine well. Palmetto and Aero are quality lowers and I wouldn't be afraid to take them into a fight. Granted, I've replaced some of the Palmetto triggers with Rock River Arms since they were kind of gritty. Other than that, I have a Palmetto 10.5" Mk18 CQBR clone and a Palmetto Mid-Length Freedom Upper that I both bought on sale as an impule buy/build and both are fine shooters and surprisingly accurate. I took them for granted because of the brand name, but now, I am thoroughly convinced.

As promised:

$20 lowers w/ free shipping for 5x & up