I've seen the most for sale in the SF Bay area. I'm looking for something bigger so I haven't payed too much attention. There are really just a lot of boats there.
If you get the right deal, you can trailer it accross the country pretty cheap. That being said, there are probably more of them the further south you go on the west coast or east coast (or gulf coast) because it's warmer and it's much more fun being sprayed with warm water than cold.