Good items to barter with are what you use on a daily basis. Food, vitamins, seeds, personal care products, gasoline, medical supplies, gardening/
construction tools, nails, glue, guns, ammunition, water filters, matches, lighters, educational, instructional literature such as learning plumbing,
welding, etc. What do you expect to need for a long time? 1,2, 6, 24 months?
Be careful if you have too much of something, you might become a target when everyone else is short of goods.
If possible, stocking lumber or firewood?
Learn a trades skill. You can barter skills for goods. Include gardening know-how. Worst thing not to have is food! Have a survivalists handbook?
A dog who can hunt or guide you to prey is always good. Perhaps an radiation suit or two
During times of severe goods shortages I probably wouldn't bother with money, gold, silver. This would only be possible during an complete
What is the cause of the complete collapse? Nuclear? Natural? Structural? Societal? Everything???
Some factors have to be considered as to what you
would need the most.
Good luck. Hope nobody needs it, though.