......Brishamash: that sounds about all ill need to insert:
“Total amount payable by the Buyer on closing will therefore be $57,000.00 (sale price less Seller credit)”.
Camasonian. It's the boat sellers broker. I don't think I'll be paying commission, Do I?
One thought comes to mind. I would NOT want the words you have in parentheses on the contract. The state in which you pay sales tax could easily argue you have reiterated that the sales price is indeed $77,000 with that parenthetical statement.
Regarding paying commission, it would be unusual for you to be paying it as the broker represents only the seller in this case, which is fine. However, indirectly, you do pay it; because it ultimately determines how much the seller is netting which impacts what they will accept.
I think it means the broker want his commission based on $77K, not $57K.
He does not care what happens to you.
I think Knot Fast and others hit the nail on the head. It is likely an effort to earn commission on an additional $20K. It might also allow them to record the sale at $77 vs $57 in their own database or other shared systems that show comps for boat sales that other brokers can see. You said earlier the broker does not need the commission. He may not need it, but he sure seems to WANT it. By this effort to base it on 77 vs 57, he is effectively trying to get 35% more commission than deserved.
There is another unlikely possibility. Years ago in real estate sales when money flowed fast and loose from lenders, one could word a contract like that to help the buyer borrow more money on the home. Similar wording (again, this was many years ago) would allow some lenders to base their loan on the $77K (the "sales price" vs the $57K. So, let's say you were getting an 80% loan to value, then the buyer would be likely to borrow 80% of $77K in the purchase, making it effectively a "no money down" deal for the buyer. Many years ago I even had loan officers tell us to word it like that so their loan could be a larger loan. They would even "wordsmith" it for us because they knew what their underwriters would approve vs not. Obviously they were on commission, too! However, those decades are long gone, so I am showing my age. I highly doubt this was his motivation, but I guess it is possible.
The broker is a wise guy attempting to enrich himself at your expense.
SURPRISE!
The sales contract needs no mention of a "credit", just the sales price.
I think FF sums it up. It is probably no more difficult than that!
I bet the seller (seller, not broker) would be agreeable to whatever verbiage you want and probably has no idea the broker is creatively looking for a 35% unearned bonus while making the buyer uncomfortable. If the seller was aware of that, he/she would probably want to put a stop to that immediately.
Good luck! I imagine you will negotiate your way through this pretty quickly.