In a nation clearly showing signs of recession, with several retailers showing declining sales and some declaring bankruptcy, Costco is thriving.
That's due in large part to the mostly unknown Costco employees who scour the globe looking for the special merchandise that will entice shoppers to buy a membership for at least $50 just for the privilege of shopping.
So sure of success, the company is even comfortable discussing when it makes the occasional mistake.
Of all the merchandise on display in Costco stores across the United States, there's one item not to be found: the Opus patio furniture set.
"It was white, the fabric on it was white," said Kim Thomas, Costco's assistant general merchandising manager for lawn and gardening, who described the Opus as "a set that we all just absolutely loved."
Costco bet that it would sell thousands. That turned out to be a big miscalculation.
"We started out; it was like a $600 set," Thomas said. "It was probably one of the worst-performing sets we've ever put on the floor anywhere."
She said the retailer finally got rid of the last of the inventory when the company opened stores in Puerto Rico and sold the set for $99, "hoping we could give it away," she said with relief.
"You know, we won't make that same mistake, but we'll make other mistakes," she said. "That's the only way we learn."
Put that way, to shop at Costco is to take part in an experiment in the science of trial and error. Its buyers will try to guess what you'll buy in bulk, from cashews by the carload to toilet paper by the ton. If Costco gets it right -- and that happens more often than not -- it gets to stay in business.
The track record, so far, has been outstanding.
Part of the secret to the success is how few items Costco actually has on its stacks and stacks of shelves. Tim Rose, senior vice president for food and sundries, pointed out that "we only carry about one-tenth of the number of items that a typical supermarket carries."
The implication is that Costco doesn't actually offer that much stuff.
But that's hard to believe, considering that Costco is the nation's fourth-largest retailer. It sold 1.7 billion gallons of gasoline last year. It is the single-largest buyer of USDA-Choice meat. And on any given day, the retailer sells 103,000 rotisserie chickens, more than 37 million a year.
What sets Costco apart from its competitors is that it only offers about 4,000 unique products for sale at any one time. Compare that to a typical supermarket, which carries about 40,000 products, or a Wal-Mart store with about 125,000 products.
What's the biggest seller of all at Costco? Toilet paper. That one single product accounts for $375 million in annual sales.
Buying only one or two of any given product leads to the secret behind Costco's success: It selects what it believes to be the high-quality products its customers want. Even when it comes to toilet paper.
"Every year to every two years, we try to upgrade the quality of this product," Rose explained. "Make it softer, make it stronger, everything that we can do to just make it a better quality product and our members, you know, obviously the reward is with the sales on this item."