HEB operates a similar model to Costco in being more expensive to the customer in a subtle way, through desirability. Their products are so interesting and appetizing that I go in with the intention of buying $30 of groceries and leave with a $100 load. Many of these products end up as local memes (tortillas, brisket queso, green sauce) they are so desirable.
Wal-Mart is the opposite. I go in to buy groceries and am always astonished to have my trip be like for $27 or something. I usually shop from the outside of the grocery (raw produce) and they are just dirt cheap.
HEB operates a series of upscale Central Market stores that are even more lopsided in price and even more interesting in selection.