By purchase contract with the seller agrees to surrender to the thing that is the subject of the purchase to the buyer, and allow him to acquire the right of ownership to it, and the buyer agrees to takes over thing and pay the purchase price to the seller. The contract to supply consumer goods to be manufactured or produced shall be deemed always as a purchase agreement.. If the parties have the will to conclude the purchase contract without the determination of the purchase price the price for which the same or a comparable course at the time of conclusion of the contract and under similar terms and conditions is usually soold is held tor the price agreed.