never heard of a pre purchase inspection costing 300 bucks unless, if I found something right away up front that was 100 % complete deal breaker.

Very hard to put a final dollar number of how much the cost of a professional survey - MY question back is how deep do you want me to dig ? Do we send off oil samples plus check for fuel and water contamination - do you want me to lake test boat if all possible, do you want me pull outdrives and check all of that out including, bellows & U joints and alignment ? Do you want me to drain outdrive gear oil and pressure check it for leaks ? Do you want me to pull props and check prop shaft run out ? - do you want fuel pressure(s) check and so on and so on as all of that adds up on top of from the basic check out.

in my case, I specifically asked for a compression and leakdown test. What I was quoted was 3 hrs to do both tests on one engine, 2 engines 6 hrs...shop rate $75-$100 so $600 on the high end, $450 on the low side. This also assumes the boat is delivered to the mechanic, if they need to travel there are time and materials cost for that too.

Add this to the cost of the survey and you are ~$800 - $1500 into inspecting the boat. On a $20K boat, that is roughly spending 5% on pre-purchase inspections. Following that through, on a $100K boat, would it be reasonable to spend $5K on a pre-purchase inspection? (I wouldn't know, I've never bought a boat that expensive).

Not knowing any better, I would think there are tiered packages much like variations at the carwash...basic, silver, gold, plat., etc. :-) ..the more you pay, the more you get.

only speaking for myself here :-)

I've had surveys on my last two boats because I bought them sign unseen. I also communicated with the sellers for a couple weeks on my most recent and well over a month on my last one, still friends wit him. If I could see the boat in person I'd skip the survey, not being able to see it though I'd never go without a survey.

I sold a boat to a guy out of state one time that couldn't come look at it. I suggested someone he trusted come look at it so he hired a surveyor. In and out in 2 minutes. Easy peasy. :D
Seriously, that guy was here for hours. Thought I was going to have to invite him to dinner.