Unless you're lazy and rich (or just busy and rich), there's no excuse for paying full price. These days, it seems, everything's on sale somewhere. But to get the best buys on basics like toilet paper, lightbulbs, and bottled water, you have to religiously read circulars and methodically clip coupons, then make time-consuming pit stops at several stores.

Or...you can shop at a warehouse club. Some 75 million Americans now pay an annual fee to belong to one of these stores — Sam's Club, Costco Wholesale Corporation, BJ's Wholesale Club — where prices are uniformly low because you're buying in bulk.

To find out just how much can be saved at one, Real Simple visited a Sam's Club in Elmsford, New York, to shop for name-brand nonperishables that can be stockpiled in the pantry, garage, or basement. We then took the same list of 15 items to a Super Stop & Shop supermarket in nearby White Plains, New York. (We also brought this shopping list to a Sam's Club and a supermarket in the Chicago suburbs.) All items were bought in the smallest sizes available; since supermarkets rarely sell items in warehouse-size packages, the supermarket prices are based on the purchase of an equivalent quantity in the largest sizes available.

And yes, you do save a bundle by consuming in quantity. Here, find out exactly how much.