Another idea: instead of selling huge batches to your local record store,
sell a few things (let's say: a hundred) to them and check back later to
find out how well they've sold. It's possible that they may have a story
to tell about one or two "special" customers who were pleased with the
"new" items that arrived and maybe there can be a kind of "hookup"
with them to find out their interests. It might take away some of the
drudgery of wondering who's out there buying what when it comes to
the stuff you want to unload. Again, this is all dependent on whether you
need to get rid of stuff fast or not. If you can casually stretch it out, you
may be able to meet new, collector friends as well as sell thru your collection.