This is a (IMO) realistic set of advice on barter in a post-event world.
https://blog.survivalfrog.com/bartering-when-shtf/Remember that there are alligators in every community and you're bound to run into some of them, particularly if you have something of value to trade.
This is where a community makes most sense. Never go to barter alone, always have several others with you who are visibly armed. Don't make yourself look like an easy mark...
In this respect, our own (NNPG) barter sessions have been in a very "protected" setting. They gave us the opportunity to experience the practice of barter, without the worry factor. They were a learning experience. Please don't expect that to be the case in a real post-event world.