Good deals come along seemingly randomly. I tend to keep an eye on prices at a variety of places for things that might be interesting and just make offers as seems appropriate. If its something I haven't tracked before, I usually want to see ~5-10 data points before I start feeling comfortable with the going cost.
Sites for tracking:
Craigslist (for anything even remotely near you, many locations)
Honestly I see the best prices and most detailed information in the last one. Normally you can read up on the owner, too, to see what kind of rider they were, which helps to decide on price. In my experience, people listing in local papers are out of their minds for what they think their motorcycle is worth, but maybe that's just a localized phenomena.
Dragging knee is for the track, and dragging tail is for the lot. --Kane Friesen
When you're in a car, you're watching a movie; when you're on a bike, you're in the movie. --Robert Pirsig
Identity theft is not Fun