Very hard to say. so many factors. Mostly revolve around, supply / demand and how badly the seller wants/needs to get rid of it.

There is some "blue book" value insurance companies would butts it at... but even that is probably "way off".

The better question (to yourself) is.... is the asking price seem fair for the value of the boat to me.

Not always possible, but i would ALWAYS suggest you take the boat out for a test ride to get a good look at its setup, rigging, check for issues... etc. You wouldn't buy a used car without a testdrive...