That's what bullion collectors like to believe. However, in your scenario you believe you can buy food (for instance) with your bullion. What makes you think someone who has a non-replacable item (food) would want to give it up for a piece of metal? Look at it the other way around, if you had 100 cans of beans with little chance of easily replacing them, would you give up some of them for a few ounces of silver? You can eat beans, silver not so much. In your Mad Max scenario your bullion wouldn't be any more valuable than a bucket of dirt. The only thing I can think of that would have any really trade value is clean water. The only non-food items with any value would be lead and gunpowder (and primers).
LOL. That's a tricky question. Don't feel comfortable answering it. But it is a fair question. Mine is worth a shinny penny. I truly enjoyed collecting the coins I have collected for the past 20-30 years. It will all go to my wife and kids. I guess I will have the approximate worth written down for them and they can decide what to do with them when the time comes.
Yes. I know its retail value based on CoinWorld. Something I had to do to get a reasonable amount of insurance from Hugh Wood. How much I paid is a bit fuzzier. MOST coins I have recorded but I got some items before I was keeping records.
I have receipts for every coin I bought. I store them in loose leaf binders. I then have another loose leaf binder to keep the index of what binder each receipt is in.
I'm not sure what the value is of my coin collection, but when I die many years from now, I'm taking it with me.