Used textbooks are everywhere. People homes are filled with it. Book publishers print copies of it yearly to sell to freshman at college or university. However, you do not have to be subjected to these expensive textbooks. There are many used textbooks being sold out there on the internet which are quite new and in good condition.
Many online bookstores are beginning to capture this part of the market, retailing used and cheap textbooks to students. It's a win-win situation for all. The seller earns money by selling his used textbook which he doesn't need, the bookstore earns a commission, and the buyer is able to get it much cheaper than that offered at bookstores.
You could be the one profiting from the books on you shelves at home too! Do not simply let these wealth of information become white elephants in our homes. They have a value and a price tag attached to it. Try selling it through online bookstores and you will be amazed at how much side money you can profit from it!