With all due respect, I cant see this being hugely popular. I think the majority of people would rather find it themselves and save the money.
Most pieces of kit are pretty easy to find, if someone is looking for something unique or rare they'll probably have done the research as to where they're most likely to be found.
Yeah, I don't see many people signing up for that service, since the feeling of finding the piece of kit you've been searching for is much greater than that of getting it through a sourcing service.