Pay attention to what they don't tell you. Garaged ski is the best, ones left on water or near it tend to be ridden more and have more corrosion. Salt water is OK if the engine was flushed after each ride. In some cases salt water is cleaner. Look for mold in side. It should be stored with front up. Lots of PWC trailers don't have jack or stand. If the tounge is just dropped and left out side the rain will go in the gills and build up in the forward part of the hull. The seat must be in good shape (its part of the flotation). 1993 and up have better designed Impeller.  One design flaw is they don't put a fuel primer. You may have to pull the flame assertor off the carb and squirt some pre-mix fuel in the carb if it hasn't been run in a while.  Don't buy the story that it has a bad starter, assume the worst the engine is stuck. Try the steering, a new cable is like $60 and they have to be run thur the hull.