If you actually believe that for most products, you don't know how to compare across stores, brands, etc. Yes, it's cheaper for some things elsewhere because A) You don't have to buy as much as a min purchase and B) what you are comparing at a cheaper store is actually truly cheaper in all ways. You need to compare not only ounce to ounce but quality as well.

I'm seriously amazed (not really) at the people who shop Costco but don't understand how and why it works the way it works.

You should also check out Lidl and Aldi if they are near you.