Top 20 Rank: 18
While Wal-Mart stands for low prices and Target embodies cheap chic, Costco is a retail treasure hunt, where one's shopping cart could contain a $50,000 diamond ring resting on top of a 64-ounce vat of mayonnaise.Costco refuses to mark up any item more than 14%, in contrast to supermarkets and department stores, which often carry markups of 25% and 50%, respectively. "We always look to see how much of a gulf we can create between ourselves and the competition," CEO Jim Sinegal told Fortune last year.
More: See how Costco rates in 8 key areas.