Decide which kind of used books you wish to purchase. The truth is there are plenty of places around that sell used books, but they may not necessarily be the books you are looking for. Garage sales, for instance, tend to be weighted toward paperback novels and outdated reference volumes. College bookstores, on the other hand, afford a much greater opportunity for the person specifically looking for a book on history, psychology or ancient Indian literature.
The Internet provides an even greater resource for purchasing used books than garage sales or college bookstores. Purchasing used books over the Internet has both a great advantage and a great disadvantage. The advantage is that your chances of finding a specific book are enhanced. The disadvantage is that with so many books at so many online bookstores, browsing becomes an exercise in patience. Amazon.com, BarnesandNoble.com and eBay are all terrific places online to buy used books, and it definitely helps to have something specific in mind.
Many public libraries hold annual or semi-annual used book sales. Depending on the size of the city and the library's collection of donated items, these sales can mean literally tens of thousands of used books at one's disposal for as little as $1 or $2 apiece. Library sales typically are very well-organized with the books separated into clearly defined categories like Health, Classics, Business, Cookbooks and Fiction. In some cases the final day of a library book sale will feature a special like $5.00 per bag or box of books, regardless of what they cost individually.
Check out Booksalefinder.com to locate cities having library sales, as well as other huge book sales. This site lists locales where used book sales are taking place well in advance so you can actually prepare a visit or vacation to coincide with one of the gigantic library books sales offering hundreds of thousands of used books. For the inveterate book sale browser, this wonderfully helpful resource is priceless.