Negotiation is impossible in the underwater scenario.
(Edited to add: It is impossible for negotiation to result in profit for the dealer. The dealer can negotiate to minimize his loss, possibly by complaining about how much he originally paid for the table. In no event can he convince a buyer to pay $50 or more for a table that they value at $40 or less, assuming a completely idealized scenario.)
Negotiation is impossible in the underwater scenario.
(Edited to add: It is impossible for negotiation to result in profit for the dealer. The dealer can negotiate to minimize his loss, possibly by complaining about how much he originally paid for the table. In no event can he convince a buyer to pay $50 or more for a table that they value at $40 or less, assuming a completely idealized scenario.)