Being perfectly honest here. Its priceless. You and I have traveled similar paths, although your boat is older than mine...... the work remains almost identical. If your son worked on it with you its even worth more in my humble opinion.
If your just looking for a denomination to put along side the boat in your head, I personally would go with a 10,000 range, and am possibly way off...... but that's my opinion. Remember, what you have is a semi rare bird. Which means the right person would have to want it to pay what its worth, to really appreciate what it is.
My 02 cents. I know mine is priceless and would have to NEED the money before I could sell it in the first place.
Mike harry