I would look on yachtworld and find the boat. I would not worry about a broker. I would just assume they either don't know anything or will say anything to make a sale. Just make an offer on a boat you like regardless of the broker and get yourself a damn good surveyor and engine mechanic and make your decision. You may actually end up with a good broker who canhelp the transaction along but it is best to assume nothing and check everything.
Since you know the specific make and model you want...why not google it and see what appears?
Also try BUCNET.COM
and Soundings Online