Your price will depend on how much you have into it and how badly you need to sell it. Unless you need the money or you can get close to book price, I would hold onto it until spring when people are anxious to buy.
I bought a '99 XP in great condition last November for $2000 with a trailer when the book value was $3000. I probably saved at least $500 by buying in the offseason. Keep that in mind because the customer will probably expect a discounted price since boating season is essentially over for you in Michigan.
Around here (Atlanta) you can pick up a single trailer on craigslist for $250. IMO, people expect a trailer when they buy a boat or a ski.
