I agree, giving ammunition to the wrong folks could be a fatal mistake.

In a real crisis, the barter item would have to have some immediate, useable value. Cans of food, can openers, soap, matches, fuel, toilet paper, basic medicines etc would be high on the list. Clothing and blankets might be tops, but my guess is that if it is serious enough to be bartering, there will be plenty of clothes and blankets laying around, previously owned by those who are now dead or missing.