Flour - disagree. King Arthur for baking vs your basic supermarket crap is a tangible taste and texture difference in baking. While you're at it, get a mill and buy organic wheat berries and save money for higher quality l, more nutritious flour. It's literally cheaper to get better quality if you are willing to mill it.
Butter- Same for butter if you're using butter as a spread. It's ok to use cheap stuff in cooking but if it's the main complementary flavor, like butter on toast, treat yo self to some Kerry Gold.