You are probably already aware of these, but just in case. Brownells has them for about $170
Numrich (gunpartscorp)has a steel one for $98
Midway has a polymer one for $35. I got one of theirs. It did the trick for me.
I tried the steel one from Sportsman's Guide. The hole centers were not correct and it look like a cast POS.
This is the best there is:
Willie Manning - Coquille Valley Machine Works
54511 Arago/ Fishtrap Rd
Myrtle Point, Oregon 97458
(tel) 541-396-6246
Willie don't make no junk.