I have lots of people come into the camera store where I work and are looking to place items on the consignment shelf. I have tried to explain that 35mm gear has dropped in price and will continue to drop while medium-format has stabilized after some big falls and large-format is about the same due to the limited number of people who were ever into it. Most of the time I say they should look for 10-20% of the price they paid for 35mm gear unless it is unique and in excellent shape; people act offended and most often leave with their gear (I see it shortly after on Craigs List or something similar where it sits with no offers). What is more funny is people who come in with digital stuff (which we won't consign for the most part) and don't understand why the 2.0 megapixel point-and-shoot they paid $800 for in 2003 is now worth $25. "But it is a Canon Powershot" they say; my retort always is "I paid $3000 for my Pentium 2 computer in 1997, what will you give me for it now?"
I did see a box brownie at a garage sale this summer, $50. Went next door and paid $15 for the AE-1 with 2 lens and a bag.