How to find good fans? I'm going to let you in on a secret. After spending hours trolling e-bay for likely specimens, I stumbled upon a site called Collector's Weekly which has a section specifically for hand fans, and what the site does is automatically search and compile all of the e-bay listings with their current prices, watchers, and end dates. They also have lots of other collectibles, if your interests lie in another direction.
Now that I've shared my little secret, don't go sniping all of the good auction items!