Ammo is a good for barter.
True; so is bath soap, toothpaste, toilet paper, coffee, aspirin, cold medicine... whatever others did not plan for. Of course cigarettes and alcoholic beverages of you don't command a moral position. One can study Argentina - The Modern Survival Manual: Surviving the Economic Collapse, Fernando Ferfal Aguirre - and get an idea of what we may well face here in the near future.
To paraphrase a quote: In the land of the unexpected the prepper is king. :^)