(1) In the case of a purchase contract in which trade-ins are being offered on the purchase of commodities, the full purchase price shall govern the classification or purchase procedure to be followed in the solicitation for bids and the awarding of the contract.
(2) The purchasing official shall determine, with respect to trade-ins, what procedure shall be for the best interest of the county. If he or she so determines, such equipment or machinery may be sold outright under the law as provided.