A beer wholesaler may sell or rent exterior signs advertising beer for use at any on-sale or off-sale retail premises. Exterior signs include, but are not limited to, signs, inflatables, and banners used to advertise a beer manufacturer’s product. Exterior signs must be sold or rented at not less than cost, as defined in Section 17026. An exterior sign that is customized for a retailer must be sold, and may not be rented.