As someone who spent the last 6 months researching and finally buying a cat, I would say any boat with strong holes and good sails and complete parts would be worth 600 if it came with a road worthy trailer. Remember to check how much normal things cost to replace - sails, tramp, etc. I think you could find a H14 in your price range that may work as well. Be patient, you'll find what you are looking for. What part of the country are you in? If you are in Texas, I can get you a list of links to scour the market with.

Oh yeah, my budget started at 500 then went to 3k. at 1500 you can pick and choose between alot of good boats.