It is declared that advertising, offers to sell, or sales by retailers or wholesalers at less than cost, as defined in this part, with the intent or effect of inducing the purchase of other merchandise or of unfairly diverting trade from a competitor or otherwise injuring a competitor, impair and prevent fair competition, injure public welfare, and are unfair competition and contrary to public policy, where the result of such advertising, offers, or sales is to tend to deceive or mislead any purchaser or prospective purchaser or to substantially lessen competition or unreasonably restrain trade or to tend to create a monopoly in any line of commerce. It is further declared that such advertising, offers, or sales by any retailer or wholesaler with such intent or effect or result are in contravention of the policy of this part.