We would like to build these for you guys, but due to a number of factors it might require us to ask for a prepay, which I've never done. I can't quote a price until we design the part, but it would be in line with other pricing for small runs of quality custom parts. I can't comment on the part sold on OptiqsHQ, but I suspect they built a lot more parts than we could sell on CPF, and I have no idea of the quality. My wild guess would be between $30 and $40.
The ones at Optics HQ won't fit properly onto Surefire M-series heads. They fit Surefire C-series bodies. You need TLS M-series heads. A full blown compatible adapter would be nice.
In terms of quality, TLS products are not Surefire quality. But they're not far behind.