In broad terms, anthropology studies what it means to be human in cultural, biological, and many other contexts. It’s omnipresent among cultures that humans were always divided between looking for benefits for themselves and sharing with others. Now, you have the opportunity to do both of them by being paid for the textbooks no longer useful for you and helping the ones needing the study materials.
In between studying human nature and development you may actually help someone develop and provide knowledge by selling them much-needed books. The prices are much more attractive than in many other places, and you earn plenty of money. Search for your textbook using ISBN or title, and we would do all the work of finding a buyer for you.