I was lucky enough to find both the primary and secondary cam chain tensioners at a local MC junkyard. Rice Paddy in Columbus OH. I think I paid maybe $20 for both. They didn't look too worn, compared to the ones I took out of mine. Most of the plastic/nylon on the old ones was gone. Probably what killed my cam chain.
I'm sure there are some used parts out there that are serviceable. Just have to ask around, and keep digging.
Luke M
Used to have a 1979 CB750L, sold it as a parts bike, now riding a slightly modified 1984 VT700C. Network/Field Engineer. Central OH, USA, Earth, Sol System, Milky Way Galaxy, Universe.