Seller contracted to deliver 1,000 barrels of oil to Buyer for $14,000. When the oil arrived, 975 barrels complied fully with the contract description. Twenty-five were contaminated and unacceptable. Oil in comparable barrels was available in the local market for a price of $18 a barrel in 25-barrel lots. Seller offered not to charge Buyer for the barrels. Is there a contract under the CISG? If so, what payment is due to the Seller?