Back in June 2012, I bought a BCM BCG from Brownells and it was 250, including shipping. Like I said, I have never been a very good bargain hunter.
I put the new BCG into my Rock River AR, and tested it with about 100 rounds, then I put the original Rock River BCG back into it. The Rock River parts are chrome plated, which makes clean-up easier. I keep the BCM as a spare. Some AR expert (forgot who) once said that 90% of the failures in an AR can be fixed by swapping out the BCG.