Last week when we went out of town we stopped at a Borders. It's one of my favorite stores and we don't have one where I live, so it is a real treat to get out of town to where they do have one. I was looking through the shelves of books and even looked on their computer to see what books I may want to purchase. I actually ended up buying a book for my husband and one for my daughter. I did find several book that I was interested in, but either they didn't have them in stock or they were more money than I wanted to pay. I made note of several of the books that I was particularly interested in and decided to see if I could find them online cheaper.
I don't know how many of you know about www.half.com. It's a great site to buy books (even textbooks), cd's, and even movies. I looked for the books that I had come across at Borders and found EVERY one of them for a fraction of the price. I haven't actually bought any of them yet, but I have started looking into the reviews on them to see which ones I want the most.
I know there are other sites that sell used books, but this is the only one I have used so I feel that it is currently the only one I can recommend. I have always found every book I'm trying to find on that site. It's also a great place to sell your used books! I've probably about $200 in the last year selling books that I had laying around the house.