Ask about the tank....as in when was it last replaced.To me, that's $1500 (for that model) off the top and I'm doing the work.
My council would be look at his asking price and then start deducting issues like soft floor, wet or weak transom, engine corrosion, electrical, steering, depending how long he owned the boat, a true documented maintenance history, not verbal, trailer corrosion, tire and bearing condition, overall gelcoat condition and package cleanliness. It has a relatively high tech engine, now out of warranty. If the engine is clean and maintained, thats at least 1/2 is asking price right there. If the hull and trailer are in nice shape $6000-$6500 would be reasonable.