When the Internet is down, economy not functioning, people struggling to survive in a collapse, cash is likely to be worthless. You won’t know what’s happened with inflation and prices, or if anyone else will be willing to sell for cash. Someone may not sell a can of beans for a thousand dollars.
Thus preppers plan on a barter economy—people trade for vital things they want. With the economy not functioning, largely just local trade (if safe to trade or interact at all), people will occasionally meet up and trade.
99% of people have very limited funds and space to store things, so it is critical to stockpile both the key things you need for survival (first priority) and ideally some ideal things to barter for something you run out of or did not anticipate you’d need. Again, having cash or even gold to trade is probably not going to work in a bad collapse—few will give up essential items for the possibility that cash or gold may again prove valuable.
It is not just a question of what will be most valuable. There are many other factors or “criteria†to consider. Fortitude Ranch, the nation’s largest recreational and survival community studied this issue and used these as the key criteria to analyze what are the best barter items to stockpile:

We then had our experts compare and rate a variety of the most popular or mentioned barter items against these criteria. The rank order of best survival barter items is shown below:

The top two may be surprising, rarely mentioned by preppers: seeds and vitamins. Yes a can of SS (Shelt Stable) food may seem like the best thing—but you’ve got to transport it to a barter site (and possibly your bug out location).
The poor rated items were gasoline, cash and gold coins. There are other clearly bad items (DVDs, clothing—lots of non essential things, or junk you can likely pick up from the folks/houses that did not survive) that we did not bother rating.
Of course, you want to have a variety of barter items. And the most important guideline for barter is—stockpile items you expect you will need and want to survive.
Dual use items are also good to have. Whiskey is not just valuable for someone who is really desperate for a drink—it’s a great medical disinfectant and may be the only emergency operation “anesthetic†you may have for that unfortunate person who must be operated on.
These ratings are for American preppers. Your country may have some greatly different situations and thus barter item value.
Just because an item is nice to have, even vital in a collapse, does not make it a great barter item.
For example, ammunition is very valuable for barter, guns—probably not. Remember, in a bad collapse, people are dying, likely most people if it’s a long, bad collapse. So for America, with quite a lot of weapons, as people die, there will end up being a surplus of durable guns. But non-preppers tend to not have a large amount of stockpiled ammo. If you’re in a gun controlled European country it may be just the opposite—having a secret stockpile of shotguns may give you top bargaining power in collapse survival barter trade.

We are amazed that some consider Bitcoin to be a valuable collapse barter item. Even if the electric grid is undamaged by the initial disaster, the workers and maintenance it takes to stay up very probably won’t be there in a collapse. And when the grid goes down, the Internet, blockchains, Bitcoin will go down. After the collapse, many currencies may not recover in the post collapse world. But the Bitcoin blockchain may also be a casualty that does not come back.
If you want to pass this information to friends and family who don’t have the Collapse Survivor App, you can direct them to the Collapse Survivor website, www.collapsesurvivor.com, “Preparedness Knowledgebase†and tell them to look at “Barter—Best Barter Items†in this indexed database.