For some time people have been claiming that cash, as trashed by governments, would start to fall off as the secure medium for purchase. Bitcoin, a system that the government can neither break nor regulate, is highly "interesting" to governments - for just those reasons. But serious collapse of the economic system will undoubtedly lead to trading, and the most valuable items will be ammo and alcohol. Cigarettes might also be included but fewer and fewer people smoke.
OTOH, ammo is becoming more available. I have noted that at least common calibres (9, 40, 5.56, 7.62x39, 7.62x51) are becoming cheaper. Now you can buy 1k 5.56 for <$500 at many sites, something that didn't exist about a year ago.
Perhaps the most interesting part of this is a comparison with the last time the nation had this kind of economic drubbing, by The Criminal formerly known as FDR. Back in the '30's, while TCFKAFDR was playing with the price of gold each morning, according to personal whim, the West suffered from serious deflation. Money was simply not available. SO, some major banks began (again) to issue bonds. Most known was Salt Lake City's banks, whose bonds became common currency in the West. This is a parallel to that story.