I sometimes use my library, but I also love buying books. I don't really have a system but I do use the library extension on chrome (which works on Goodreads and other sites) so I know easily if a book is at my library (or scribd or hoopla) or not. Many books I want to read are not at the library. I do buy cheap used books from thriftbooks sometimes to. They don't all have to be new. :)