According to Costco, an average warehouse carries about 4,000 products compared to the 30,000 found in most supermarkets. A supercenter can sell up to 100,000 products.
By only stocking a handful of toothpaste brands, as opposed to the plethora you can find at most stores, suppliers are forced to compete with each other to win a place on Costco's shelves. And, suppliers want to make the cut — because there are only a few options, customers end up buying a lot of the brands that Costco decides to stock.
Costco name-checks its "tremendous buying power" as key to its low prices on the company's website.
"By carefully choosing products based on quality, price, brand, and features, the company can offer the best value to members," the website states.