if you're talking about post-apoc as a fictional genre that explores themes of isolation and alienation, it makes sense to not have an economy. So parables and more impressionistic fiction etc. Mad Max, The Road and so forth.
If you treat post-apocalyptic settings with realism as a concern, then you have to look at how humans behave in similar situations. There are post-apocalyptic regions in the world and there have always been. War, famine, plague etc, creates similar situations every day. Apocalypse is a matter of perspective to a certain degree. People repair, trade, and negotiate in order to survive. These actions create complex economies. Canticle of St. Leibowitz shows civilization reviving after the apocalypse.
Anyway heres some vaporwave
