Preferably a Colt, Stag, or RRA aluminum unit, though I would consider a Bushmaster plastic one. I would also consider the Magpul unit, at the right price. Email me please.
Edit: No shit,
, I could buy one from Bushmaster or any other supplier. The same could be said for everything else in the EE. This is mutually beneficial and I don't have to pay $9.50 to ship a $5 part.