You might check out your local library & see if they have book sales - I volunteer at our Friends of the Library and we have weekly book sales at bargain prices ($1. & .50!!) - a lot of times I find practically new books. I know a lot of libraries only have annual or once a month sales - we fortunately have a large space & have something like 30,000 volumes! A lot are donated, some withdrawals from the library system, etc.