Like WD says depends on a lot of factors. Anything film is fairly cheap used there are a few exceptions though but usually rare or high end film cameras like Leica M3, Hasselblad, etc. Lenses can keep their value but again so many variables to take into consideration that it is hard to say what you would get, do they fit modern bodies, is the glass scratched, what shape it the lens body is in, etc.

Unless it is fairly new, a generation of two old you can get ok coin for it, anything older than two generations the price on them starts to free fall but not in all cases but most as far as Camera bodies go, lenses are much harder to price because good glass is always good glass but will those lenses have a market for them and if so what are people willing to pay and other factors to consider.

See what you have, look at the condition, go to ebay, craigslist and any other forum that sells used gear and get an idea what people are asking for what you are selling. Selling something on ebay over what the retail value is I will take with a grain of salt, just call me skeptical. I am sure it happens but probably so rare that I would liken it winning a lottery as far as it pertains to your chances of doing it.