Mega lowers are also very nice, if you can locate them. About the same price as Stag and teflon coated. All around, they have some of the best machine work I've seen on a lower. Stag and RRA are also very nice (I just like the finish on the Mega lowers better).
I purchased my Mega's locally. They can be hard to find online (as can lowers from other manufacturers. Everyone seems to be out of stock lately)
www.carricozarmory.com/mega.htm seems to get Mega's with some regularity.
www.eaglefirearms.net/stag_arms.htm Carries a lot of Stag and Rock River.
No need spend lots of money to get a quality lower. These companies make products that put some of the big names to shame, for half the price.
Del-ton will treat you well.
I've also had good experiences with Eaglefirearms, RB precision and Rock River.