the truest free market may involve bartering. Some useful items that may be in demand: batteries, small propane tanks, soap, seed packets, spikes, sharpening stones, lantern mantles, extra butane lighters, extra flashlight bulbs, aspirin, etc. I am sure there are things around your house that would be useful if normal commerce shut down. I would inventory and place them together in one location ahead of time, so that I could grab them in a hurry. Call it your hope chest. Hope you never have to use it. You may not have time to search for something you know you have, but forgot where you put it.
“You may not have time to search for something you know you have, but forgot where you put it.”
That is my problem - too much crap and disorganized. The last time we had a winter storm come and knock out the power for a week at least I had a few days warning to get the basement cleaned out for sleeping around the pot-belly stove, getting supplies in order, etc. Didn’t need to go to the store for anything though.
Heaven forbid if something happened where I had a half-hour to leave.