With a boat... it depends on the region, and the time of year. Since we are in early summer... the prices are high. (so that's good for you)
All you can do is post it up, and see what kind of interest you get after a week or two. Locally... I've seen clean SK's sit at $4500, but in some places... they get sold quick for $6k.
So... price it a little high, and gauge interest.