I don't know how else to understand "When comparing things like bread and butter, the ultra processed versions are much cheaper.", other than as a claim that ultra-processed versions of things like bread and butter are much cheaper than non-ultra-processed versions of them.

How much does a loaf of white bread cost? How much does a load of whole grain cost?

Whatever it is you are trying to argue in your comment, it has nothing to do with the cost comparison I am making.