A few years ago, a lot of college photography classes were still teaching film and darkroom -- so there was a market for 35mm SLR bodies and lenses (although the demand was from college students who couldn't afford to pay much.) I have an Canon AE-1 body in excellent working condition and I had to drop off a lens for repair. I asked the owner of the camera repair shop what a used AE-1 body was worth... about $125 USD. He had lots of 35mm SLR bodies all in that price range (the Pentax K1000 was a very popular camera body among students... that'd be a little less than $100).
He had one single "new" (never used) in box Canon AE-1 Program going for about $400... but he said that body was being sold "on consignment" (he wouldn't buy the body to resell it because he did't think they'd be able to get $400 for it.)
While this is all "new"... complete with boxes... keep in mind that there's very little demand for 35mm SLR bodies, accessories, or lenses. The classes that used to teach film and darkroom are mostly moved on to digital so it's getting tough to find anyone who needs or wants a film body other than for nostalgia or the feeling that they're "retro". I still hold onto my Canon AE-1 and two lenses, but I never actually use it anymore -- I only shoot digital these days. I even traded a guy my original Canon T1i for a Mamiya 645 medium format, thinking I might get back into shooting medium format. But even that sits unused.