The place to start is with the broker. Get your ducks in a row and ask very specific questions in writing about the boat and its history. Ask for pictures of anything the online listing does not show...ask for a copy of the last known survey. Visit the owners group and find out what DOES go wrong with these boats and then ask the broker about those things. Once you are satisfied, then...
Make sure the broker knows that this is an expensive trip for you and that you will be quite angry if you make the trip and find thing not exactly as described. Do this on the phone...not via e-mail.