Actually that's not out of
line and your surveyors offer is a very good one. Surveyors are professionals with a lot of experience and knowledge, that is what you are paying for. The surveyor is in a position to find many things, including significant problems, that you are probably not in a position to find. A good survey will ultimately save you a ton of money by being able to negotiate further with the seller or avoiding a real mess of a boat. I would not even think of doing it myself.
As far as multiple surveys before you buy a boat, I had 3 done before I bought mine. Money well spent as each boat I turned down would ultimately not have suited my needs or cost me a fortune in repairs. It sounds like a horrible scenarion but in the end it's best for you. The only way to minimize that is to do as much due diligence on your own to narrow down your choices.