一锤子买卖 A one-hammer deal. A single transaction with no thought of the future. The word is critical. A dictionary example reads: “You cannot do only one-hammer deals.”
回头客 A customer who turns the head back. A customer who comes back to the same seller.
老主顾 An old customer. A customer with a long trading relationship.
世交 A friendship between two families that has lasted two generations or more.