There was an article somewhere not too long ago about a bookseller in Saltaire who gave figures of his sales on some sort of social website and that prompted people to go to the shop and, temporarily at least, boosted his sales.  The problem seems to be general lack of interest in reading, and for those that do read, eReaders are providing an alternative.  There is a website called webuybooks (is it alright to mention that here?) that might be worth looking at if you're not a dealer.  If you sell on eBay at 99p, by the time the fees are deducted, I don't think there'll be that much of a difference in price got, and it's a more straighforward transaction.  Having said that, they don't accept all books.  I haven't used it myself, so I can't comment on if it's any good.