Re: 1987 model
Well one thing is that it really depends on where you live. Here in Wisconsin boat prices are very inflated compared to other regions. The best way to see what it is worth is to check the local classifieds and see what something similar is going for. At some point boats sort of "plateau" in their worth. So anything near yours in condition and age will give you a good idea. Simply it is worth what someone is willing to pay.....
Painting kind of depends on how bad the paint is. If its down to the metal you are going to have to etch the aluminum really well to have any hope of new paint bonding to that surface. If you are painting over paint, don't remove it, just wire brush off the loose stuff and rough up the stuff on there to give you a bonding surface. The paint on there now is probably going to be bonded better than anything you can put on it. IMHO