Some good information posted so far. As someone who has both sold records in bulk and also individually on eBay, I would add this: How much time do you have to deal with this project? During a stretch when I was unemployed, it made a lot more sense for me to list a bunch of albums on ebay that only went for $5 a throw. On the other hand, working full time and always having stuff to do, I only list albums on eBay that I'm pretty confident will fetch a lot.
So, depending on how much time you have, you may want to eBay only the more desirable titles, and sell the rest in bulk to the record store.