once again, when we moved, we did this exact thing. it was a lot of work, listening to sob stories about not having money, trying to find people and/or apologizing for bringing up their divorce. these were film negatives. we probably made a $1000 or so. so with a little work, at least when you are primarily in the wedding business, you could make a few bucks. but people back then weren't just handed their images, so they bought the ones they wanted and have pretty much written it off. I should add that we called at the beginning of December, hoping the families would have some spare cash laying around...ymmv
in today's world, everyone wants their negatives (at least in weddings, and I believe in general as well). So...we build into the package their negatives and walk away. what's left to sell?
I think you should try it and report back. A couple hours one evening and you could probably figure out how it is going. If it's a family or kids, unless someone died, they would rather spend the money to get a more recent photo (hey, maybe that's your real nugget). if it's a senior, they most likely already bought what they need/want. my mom bought my senior pictures, framed them, hung them on the wall and have never really looked back, neither have i asked for them.
and warren...i'm well known for my "hard" skills.

it's bc i work with 90% men who are engineers. you learn to appreciate people who don't beat around the bush or mince words...