Guns are fun. But they're just tools. Sometimes lifesaving ones, but not really different from hammers or hacksaws. (The former are just effective farther away than the latter.)
Ammunition. Water. Food. Medicine. Any other consumable supplies? Those are commodities.
But something that's both a tool, and a consumable, and will get you all of the other things you could ever need, or want, is the indispensible item.
Nota bene we did not say "cash". Cash is nice, but it's not money. In fact, it's explicitly something commonly accepted by people AS IF IT WERE money, thus not money, per se.
Gold is money. Silver is money. Other precious metals (nickel, copper, platinum, etc.) can be money. US dollars (nor Euros, British pounds, Swiss francs, Japanese yen, etc.) are NOT money, and haven't been since they stopped being readily exchangeable for actual specie.
Other things (jewels, bonds, stocks) are worth money, but they aren't money either. Nobody prices gas or milk in gallons per carat, for instance.
So as you're stocking up on canned goods (both in #10 cans, and in olive drab ones), and storing water, fuel, and all sorts of consumables from pins to nails to bolts to lumber products - you are working on that, right? - make sure you're storing money. And cash. In a cache. Or ten.
[BTW? Cache? It's also pronounced cash. Not cashay. Don't sound like the prepper version of Dubbya when he talks about "nukular weapons". Cachet is a perfume. A cache is where you store stuff. They don't sound the same. Ever. Just saying.]
So part of your efforts should include adding "junk" silver (i.e. U.S. coinage prior to 1965, which is 90% silver by content), and gold (ideally in fractional ounce denominations - 1/10th oz., 1/4 oz., etc. - as coins worth $1800 and up for full ounces are a bit too concentrated for everyday items) to your stockpile(s). I made that plural, because you shouldn't keep all your nest eggs in one basket. In any sense.
And, as every devotee of Dave Ramsay knows, have a cash reserve.
Six months' gross income is a worthy goal. It gives you options, not least of which is "F**k You" money, to cope with a bad boss, a bad situation, or a bad location. Anything you can't solve with six months' cash is pretty much catastrophic levels of problem. Probably 90% of life's problems are readily solved by a six month float.
Any or all of this should be stored, safely and securely, and not in places or institutions that do not have your best interests in mind. IOW, safety deposit boxes suck. Try getting into yours after a disaster, or a bank run. Or after a tax lien. [Hint: It ain't happening. And you're therefore screwed. Possibly terminally. Think about that.]
A safety deposit box is for Grandmother's pearls, or items of personal and sentimental value, not necessarily of financial value. Anything in them can be seized, stolen, confiscated, etc., at times and means out of your knowledge or control. Thus it isn't safe in any sense. Except from you, not for you.
So your emergency cash stash should be ready to hand. It's your bugout bankroll, or most of it. Cash will likely solve most of your small problems, and still be accepted (howsoever briefly) in major disturbances to society. IOW, long enough for you to get from current home to safety, if they suddenly cease being one and the same place.
The melt value on a roll of silver dimes is currently about $100, btw. A shade under $2/@, at the moment. In 50 years, it will still be 50 pieces of 90% silver. The $100 in a crisp Benjamin will not be nearly as valuable in 50 years' time, or even in 20 years. Bet on that reality. Ignore that truth to your own financial peril.
FTR, US$100 in gold from 20 years ago is now over US$677 in gold. Put the other way, $100 in cash now, used to be $14.75 in cash the summer before 9/11. (An ounce of gold then was about $271, and it's $1,836 right this minute, for that same ounce.) That's how much inflation has destroyed your cash, even since 2001. Now see if you can guess why the price of everything goes up faster than your salary, and faster than Fedgov can print fiatbux, 3 shifts/day since ever. Gas at $4/gallon is frightful? It could just as easily be $27/gallon. Let that news settle in for a minute, and bathe your financial consciousness. Your savings and income is being inflated away towards Weimar/Zimbabwean rates of loss while you sit reading this. And it's only going to get worse from here on out.
Find some places you can stash small hoards of money. (Actual physical money, in your sole control. Some B.S. account where they show you a piece of paper, for gold not in your hand, is worth less than the paper and ink to make it.) And begin acquiring them, and stocking them appropriately.