KEH is not a good option. They do not thoroughly (if at all) test their cameras. I've had numerous returned bodies with them.
The best route is eBay. Avoid any camera with any of these remarks:
- "I know nothing about cameras"
- "It was working when I last used it years ago"
- "Sold as-is"
- Or has blurry photos of the gear
What you are looking for is a seller who has used the camera recently, has owned it for a while, and can show you sample images. The last may not be possible, but it never hurts to ask.