A price-marked product is one in which the recommended retail price is printed on the actual product. A common example of this is on cans of soft drinks. It in also used extensively on the entire happy shopper range of products, among others.
Research shows the consumers trust a price-marked pack more than the price on a shelf edge label, presumably because it confirms that they are getting the product at RRP and not a higher mark-up. Variants of the same product are also available at a higher price mark, and therefore a higher price.
For instance, one wholesaler is currently selling 24 Pepsi cans price marked at £0.49 each for £5.69. Higher price marks are more expensive, and the un-price-marked packs are more again at £7.49.