Something to think about is how readily available are the books, vs. the demand for them? If it's a film reference book you know that you won't look at again that is not currently in print, chances are someone out there might be looking for it. If so, rather than go through a local bookstore, Ebay or the classifieds here might provide you with an outlet. (Like Tim pointed out, a used bookstore is not going to offer top dollar. The same goes for used VHS and DVD at video stores, no matter how good you've taken care of them.) Over the years, I used to pick up the novelizations of films if I enjoyed the movie. For the most part, I found I rarely ever reread (or, in some cases, even read) those, so stopped buying them and got rid of most of the ones I had. (Although I did spring for the BATMAN BEGINS novel, because it was written by former Batman scribe Dennis O'Neil, and I figured he would bring more to the table than most writers would.) On some of the older movie tie-ins, with photo inserts, I found that some younger fans of those films (who were either too young or not born at the time of the film's release) were interested in them because many movie novelizations rarely get reprinted or do not include the photo gallery of the original. (For example, the STAR WARS novel not only included photos, but they were COLOR photos, which was very uncommon at the time.) Cyberspace certainly gives you more options, when it comes to spring cleaning, as you can reach a broader audience.