They were expensive when they were new but as soon as you scratched them up, put some use on them, they lost half their value at least. The "sport" has changed now and few people are even in the market today for your boat(or mine), and now we have a glut of used boats. This dismal supply and demand is the reason for plummeting boat values despite inflation.
Houses(more the dirt they sit on) overall will increase in value over time with the cost of labor and general inflation. People need housing, not old skis.
The only thing that gives an edge to an older boat in this market is a high degree of maintenance. That maintenance is tied to inflation for most people(few can achieve what a good boatyard can do if given the carte blanche treatment). And that results in even less value at sale time for the owner. It's a bad deal all around....
So Dan, if you were buying your boat, how much would you feel good about paying?
You might look into Dave Gibsons angle. Everybody needs housing. Advertise in Apartments for Sale on Craigs list. "Waterview!"