((a)) ** .—** This chapter does not apply to the purchase of materials, supplies, articles, or equipment that may usually be bought in the open market.
((b)) ** .—** This chapter does not apply to any of the following:
((1)) Perishables, including dairy, livestock and nursery products.
((2)) Agricultural or farm products processed for first sale by the original producers.
((3)) Contracts made by the Secretary of Agriculture for the purchase of agricultural commodities or products of agricultural commodities.
((c)) ** .—** This chapter may not be construed to apply to—
((1)) the carriage of freight or personnel by vessel, airplane, bus, truck, express, or railway line where published tariff rates are in effect; or
((2)) common carriers subject to the Communications Act of 1934 ( et seq.).