(s) no wholesaler or processor shall offer for sale, sell or supply the regulated product to any retailer, peddler or other person who has, within the preceding seven days, to the knowledge of the wholesaler or processor, his agents or servants, sold, advertised or offered for sale the regulated product at a price less than the price paid for the regulated product by the wholesaler or processor to an agency, or the current day’s price at the time of sale, advertisement or offer, charged by the same agency for the same type and grade of product, whichever is the lesser;