Have popular grocery stores mislead our knowledge of value?

Most people in the US shop at a store such as Wal-Mart for their groceries. You can get a cart full of groceries for about $100. A great bargain. If you bought a cart full of groceries at, say for instance, Whole Foods, you’d be paying more than double that for similar products. When shopping outside of big chain stores, we are often surprised at how expensive the items seem to be.

But are they truly expensive, or are we just no longer aware of how much things cost because of corporations such as Wal-Mart?
Which range of prices do you believe is more fair all around? Consider the fact that the growers and creators of the product, the brand, and the final seller all need a cut of the profits, and the consumer wants the best price possible.

Also, where do you tend to buy your essentials?