Well, I don’t know the stores you mention but at my WFs the prices are astronomical.
It pays to be an educated shopper. And in the DC example, the differences were about 10%.
I'm not much for buying "organic", but I know that HEB isn't cheap on everything either (they have a rack full of "designer" spaghetti sauce that will cost you $8 a bottle if you want it. Whole Foods' own brand(organic or non-organic) will run somewhere between $3-4. HEB's store brand runs $4-5.
I cite HEB because that's who they compared against and who I'm familiar with. People are free to shop wherever they think they are getting a "good deal".