Expect to buy some new batteries yourself. Watch the classified ads in the newspaper. Be sure you can get a refund if something doesn't work. Don't pay more than a camera store would charge for a similar used camera. Be sure to ask for the instruction book.
Careful owners keep the book and know where to find it.
Photo magazines like Shutterbug and the Internet have large selections of used cameras and lenses for sale. Using a seach engine like goto or google . Type used camera, click search , and it will finds lots of sources. Here is a directory of used camera sellers . Any newsstand has Popular Photography or Shutterbug .