Sam Walton, founder of Walmart, was a retail genius. One thing he would do is advertise a product such as a microwave at a knock-down price. Consumers would come into the store to examine the low-priced microwave. Next to the low-cost microwaves, Walmart would position some better quality, higher-priced microwaves. The idea is that consumers will be attracted to the store due to the low-priced product but that they often upgrade and purchase a higher-priced product once they realize that it offers better quality. Such a method is completely legal as long as there are enough low-priced products available that consumers can choose from if they desire. Sam Walton used what type of pricing strategy