Used books are everywhere.  Used books are in people’s homes, used books are in libraries, used books are online, in thriftstores, at garage sales, in your newspaper, in…well you get the picture.  A lot of these books are firewood basically, that you do not want in your house or office.  Others can net a 10,000% profit. Just remember, when looking for books, never buy without knowing its value.  Use scout tools such as the free one offered at bookspy.net.  Here are a few ways you can net used books:

1. Craigslist- Run a craigslist ad offering to buy used books.  You will get all kinds of responses to this.  Again, check before you buy or offer low.
2. Local Newspaper Ads – Again, run an ad offering to buy books.  You will get everything from little old ladies offering you 500 romance books, to college students looking to make a little money.
3. Booksalefinder.com – Hit up your local friends of the library book sales.  This is often where the big money comes in.  Just be aware that some libraries are looking up books themselves and keeping the good ones!  Skip over these libraries if you find any doing this.
4. Thrift stores – These tend to get picked over quickly by other booksellers, but if you live in rural area, or there are not many booksellers in your area, these can be a goldmine.
5. eBay – Finally, you can look for underpriced books on eBay.  This one takes a bit more time investment, and a bit of hard work.  Ocassionally it can pay off though.