Occasionally people ask me is it worth the cost to have a pre-purchase inspection done on the boat they are considering. My answer to them is that usually there will be a number of issues identified, and quite often the cost of repairs required is 10 or more times the cost of the inspection fee.
I was contacted recently to assist someone get his generator up and running. (They didn't have pre-purchase inspection done). After some investigation I referred the diagnosis to a marine mechanic. At some point prior to the sale, the genset had a major internal failure and now requires a rebuild or replacement.
As a part of a thorough inspection process, the fact the generator was not able to be started would have been identified and further investigation recommended likely saving the owner several thousand dollars of costs.