Section 14. (a) It shall be unlawful for any retailer, with intent to injure competitors, destroy substantially or lessen competition, to advertise, offer to sell or sell at retail cigarettes at less than cost to the retailer, or for any wholesaler, with intent to injure competitors, destroy substantially or lessen competition, to advertise, offer to sell or sell at wholesale cigarettes at less than cost to the wholesaler. Any such retailer or wholesaler violating this subsection shall be punished by a fine of not more than five hundred dollars.

(b) Evidence of advertisement offering to sell, or sale, of cigarettes by any retailer or wholesaler at less than cost to him, shall be prima facie evidence of intent to injure competitors, destroy substantially or lessen competition.