don't do it. think of the survey as the 'hand' you are dealt. you wouldn't show your cards around at the poker table, would you?
the only thing i would reveal to the selling broker is the problems the surveyor
found. those are your 'ace' cards.
you don't need to offer any explanation to him, regardless of how he cries and whimpers. if you must, tell him to give you five new crisp hundred dollar bills and you'll give him a copy of the survey.
i can think of one good reason the selling broker wants to know the price. surveyors nearly always overstate the price of a boat. the selling broker can then say to you, 'see, i told you it was a great buy!'.
remember; this is business, not a gathering of corinthian yachtsmen...