Copied from another page and too lazy to edit.
Tactical Machining (forgings)
http://www.tacticalmachining.com/80-...receivers.html
Colfax Tactical (Forgings)
https://www.colfaxtactical.com/ar15.htm
Ares Armor has ones from forgings, and has their ATF determination letter.
Bare, $80 each
http://www.aresarmor.com/install/eco.../TACMHRW1.html
Type III Hard ano, $90 each
http://www.aresarmor.com/install/eco.../TACMHL15.html
Also, RifleGear.com appears to have the TacticalMachining ones in stock at the moment...
http://www.riflegear.com/showproduct..._campaign=feed
Quentin Laser always has the billet AR-15 ones. Rumor has it that they are going to start making their AR-10 variant again soon. Lately, their customer service has been lacking.
http://quentin-laser.com/store/produ...roducts_id=159
These guys have engraving too...
http://www.shadowopsweaponry.com/pro...ower-ar15.aspx