<p>try doing a search here for "used textbooks" and you should come up with plenty of names of places. The problem is that you rarely get close to what you paid for it (especially if it was from the bookstore and it was new)</p>
<p>If you go to bigwords.com and enter all the books you have to sell, it will search all the companies (including amazon and half.com) and find your highest selling combination. It will also find your lowest prices if you are buying</p>