I saw the following at another boat building bulletin board and thought it was pretty good:

A classic, handcrafted boat from, say 1900 is worth a lot of money. A newer, but still old enough to be classic, boat will still be quite valuable but probably only half the price of the antique.

Newer still - a boat you built a couple of years ago - this is the bottom of the price curve. It's a used homebuilt and not worth much. One you just finished is a new homebuilt worth a bit more. One you haven't built yet but presell is a custom job and the price climbs quickly back into the stratosphere.

So the secret is only to build boats a long time ago or soon but not now or recently... ;->

Jim