The price of the parts is determined by the buyer and seller. After they are discussed together in the price the seller has offered buyers in a given format or assigned by the buyer.
The price of the parts is determined by buyers and sellers. After a discussion in which the seller has offered to buyers in the prescribed form. Or assigned by the buyer
The price of parts are determined by the buyer and the seller. After a discussion in the price that the seller has offered to buyers in a set or assigned by the buyer.