Well I belong to a book club, but I usually only buy a couple of my favorite authors from them since they are all hardback books.
Most I buy from a store, but I usually buy from Wal-Mart, Sams, or Target which knock a couple dollars off the list price.
I used to have a really great small neighborhood new/used bookstore that I went to, but I moved about 45 minutes away, so I don't go there anymore. But I sure do miss it!!!