Midwayusa.com has DPMS AR-15 LPK in stock, limit one per customer. About $72 after shipping if that's all you buy, but I know a bunch of guys have bought bare lowers lately. Get them while you can.
http://www.midwayusa.com/product/877204/dpms-lower-receiver-parts-kit-ar-15
http://www.midwayusa.com/product/877204/dpms-lower-receiver-parts-kit-ar-15