Have you ever tried an online book exchange? You can trade your old books with other people for something else you would like to read. For the cost of shipping, you can be happily reading more great books. Some even allow you to trade music, movies, textbooks, and more. What a great way to recycle and to save money.
I've tried it but never could find interesting books. I'm very particular about the kind of books I read. I've got some good movies through such [similar] exchange programs though. As for books . . . someone like me who reads only books which have been recommended by friends who read humor books [people I know can recommend something that is funny], online book exchange sites/programs can't provide what I seek because in most cases the books I want to read can't be found anywhere on the net.
I would only trade text books as i like to keep all my books. Books are cheap enough to buy your own copy or to find in the library so I can't see how it can be worthwhile with postage costs being so expensive these days. Text books are the only books I don't choose to buy that I would trade as often I don't need them afterwards. Maybe people that don't have access to the internet or libraries would find this useful, but for most people it would be time consuming and also compromising on what you wanted in return.
I guess I had good luck. I found some books I liked and was able to trade those I no longer wanted. If I kept every book I read, I wouldn't have room for anything else. I think it would be especially good for textbooks. They can be very expensive, and like you, I wouldn't really keep (most of) them around when I wasn't using them any more.
Actually I've never tried this but since I've started reading again I might actually try it. Although if the book I wanted were at the library I would probably go there first since I can get it for free. I would probably only do this if there was a particular book I wanted to read and couldn't find it in the library.
