Aero Precision's website has these two complete lowers in stock. Click the links below.
Black M4E1 Complete Lower Receiver w/ MOE SL Grip & SL-S Carbine Stock $289.99
Black AR15 Complete Lower Receiver w/ MOE SL Grip & SL-S Carbine Stock $284.99
Black M4E1 Complete Lower Receiver w/ MOE SL Grip & SL-S Carbine Stock $289.99
Black AR15 Complete Lower Receiver w/ MOE SL Grip & SL-S Carbine Stock $284.99