I add them to my Amazon wishlist to keep track of what I am intending to buy, then usually check half.com or ebay. If you frequent used book stores, they someti

I add them to my Amazon wishlist to keep track of what I am intending to buy, then usually check half.com or ebay. If you frequent used book stores, they sometimes have good deals. I also sometimes order books for my Kindle, but that's suboptimal since I like physical books.