If you were really serious about this, you’d be hoarding .22 ammunition. You’ll be able to barter for anything with a handful of .22s.
Yes, but how many handfuls of 0.22 can you carry or store safely? If you're looking at protecting several hundred dollars of wealth, ammo is the way to go. If you're looking at protecting several hundred thousand dollars of wealth, you've already got plenty of ammo, now you're looking at something with a decent value to weight ratio, and that's gold.