It is unlawful for a manufacturer of spirits, wine, or malt beverages holding a certificate of approval or the manufacturer's authorized representative, a distillery, brewery, or a domestic winery to discriminate in price in selling to any purchaser for resale in the state of Washington. Price differentials for sales of spirits or wine based upon competitive conditions, costs of servicing a purchaser's account, efficiencies in handling goods, or other bona fide business factors, to the extent the differentials are not unlawful under trade regulation laws applicable to goods of all kinds, do not violate this section.