I just want to reiterate - you don't need to buy huge quantities at Costco. My husband and I now live in a 1400 sf house with almost no storage - certainly without a pantry or anything. It's just the two of us and we shop at Costco all the time.

The largest things I buy are a 78 oz container of coconut oil, 18 ct eggs or large spice bottles (cinnamon, salt, pepper, chili powder...the things we use in quantity) and while they last a long time, they don't take up that much more room than a regular sized container. You certainly don't need to buy cases of mayo or anything. Maybe that's how these stores used to do it, but now most food things are packaged in a reasonable size. At most, something might come in a double pack (like ketchup) where you have to store one of the two bottles.