I bought and sold 3 boats on eBay. I concur with above that it's better for the buyer than the seller, but boats don't always hold their value, either. I got three really good deals when buying, and sold for what I could get when selling.
Just put a reserve price on it, and if you don't get the reserve (the minimum that you will sell it for), then you don't have to sell it.
Good luck!