Sometimes, depending on what brands you prefer. But you have to be careful, because sometimes, for example, paper towel is cheaper at the supermarket, sometimes it's cheaper at Costco. And of course, buying the big quantities only works for non-perishables, or for big familes, or people with large freezers.

We had a membership back before I became allergic to Sucralose - as Fruit2O was cheaper by the case ther than by the 6-pack at the gracery store. But we let it lapse because I cannot drink Fruit2) any more, and water is something that you just have to watch the prices, and buy a bunch when it's cheapest.