How old is it?
How long have you had it?
How often did you use it?
How often did you run it in the salt?
Do you have the freshwater flush adapter?
When was the last time it was in the shop?
How often did you wax it?
Ever taken on water?
Ever had electrical problems?
Was it covered when not in use?
Does it catch fish?

Those are just a few I can think of. Don't forget to take a good look at the trailer, too. You can check the value of the boat on the net. I can't remember exactly where, but it's boattrader.com or something like that.

Good luck.