I saw this article on Yahoo Finance comparing the two stores.
I do understand the comments about the time value of money, but I feel I get a great return on that at Costco. And I don't believe I spend as much time there as the author of the article does, except for times when I am deliberately surfing the store to find new products.
And I can't readily buy through Amazon take and bake pizzas, romaine lettuce, black bean burgers, potstickers and innummerable other items I buy fresh, frozen or refrigerated at Costco.
Don't get me wrong, I do think for some people Amazon has a valid business model, but for so many of the grocery and other items we buy, Costco just can't be beat.