That would be rational. I am assuming that even in a post-apocalyptic scenario, people will not be rational. I imagine people being willing to pay an awful lot for the experience of tasting M&Ms again and for a few brief moments being able to pretend that everything is just like it used to be.

Though now that you point it out, maybe I would rather buy rice and beans so that I could be more useful to people, rather than just maximizing profit. Or better yet, stock up on both kinds of goods.