fleaBay will get the biggest audience. Otherwise try somewhere like rangefinderforum.com (yes, they have MF enthusiasts who don't use rangefinders).
Price depends what make the stuff is; I sold my Bronica stuff for a comparative song in 2002, but it's *really* worthless now. In that case it's because Tamron stopped making and supporting it, not just because it's film; Mamiya and Hasselblad stuff has held up better. I would never buy a second-string brand again.