Preparing for societal collapse
If there is a total collapse of society, goverment and economy people are really going to be on their own. Groups and towns will band together for protection from roaming bands of brigands, neighbor will depend on neighbor once again. Many of the goods most of us are used to having available will not longer be available or very hard to obtain.
If you plan ahead and happen to have extra of these goods available it will definitely be better than cash money. And possibly more valuable than gold. It doesn't matter how much gold a person has on hand, if they are hungry, food becomes a lot more valuable.
Everything is going to become much more valuable but here's a list of 10 good canidate of things to stock up on. These are things that will be valuable barter and trade items but by no means should you limit your emergency stockpile to these items.
Food and water
The food that you do stockpile should be rotated through your normal consumption routine to make sure it doesn't get to old. The benefit of this is that you'll be used to eating what you have stored. Focus on things that will have a long shelf life like canned and dried foods.
Before a collapse use some frugal shopping skills to reduce the cost of creating you stockpile.
Having the skills to obtain new, safe food and water can help immensly at keeping your reserves well supplied.
Warm Clothes, boots and blankets
For your own use collect clothes in your own size, but if you have extra you may well be able to barter them with others for something else that you need.
Blankets have the advantage of being useful with no sizing involved.
Clothes like socks and sweaters as well as blankets that are made from wool or alpaca will maintain their insulation value if they become wet. Fleece blankets and sweatshirts are nice and warm and will be cheap to stock up on but if they get wet will not be very comfortable to wear or use.
The cordless drill may be a real handy tool to have around, but if there's no electricity to charge it you'll want to have some sort of alternative. Our ancestors built some great master pieces without the use of power tools. Along with the tools be sure to stockpile hardware consumables like nails and screws.
Hard liquior like whiskey, brandy or bourbon will keep indefinitely as long as it is kept sealed and in a cool dark place. Stock up on smaller bottles which will be easier to barter with for other items. This can be a luxury item as well as a medical item along with a good barter item.
Medical and First Aid Supplies
Most drugs and medicines will last past their expiration date, but they wont last forever. Having an extra supply of them on hand will help through the period of adjustment.
Gasoline for vehicles like cars, trucks and tractors will be valuable in the short term. Unless the flow of gasoline is resumed the value of it will spike when the realization that it can't be had sinks in. This should probably one of the first things you barter with if the collapse looks like it will be very long. Not only is the shelflife of gasoline fairly short, but people will quickly quit using vehicles, they'll either be out of gas or the vehicle will quit working. Maybe you can trade some of the gasoline for a horse or mule.
Don't forget other forms of fuel, like propane. A propane tank can supply emergency heat in severe situations or used as a heat source for cooking or metal work. Keep in mind, though, that once your supply is gone, it's gone.
Open pollinated seeds
A good scenario to follow would be to keep at least two years worth of seeds. This way if there is a bad year you'll have a backup stash of seeds.
Start your garden as soon as possible, these skills aren't something that you can just pick up overnight. Practice your gardening skills before they are needed and you will be much futher ahead.
Not only may they help raise your own moral, they may also be useful for barter. Things like chocolate, canned bacon or even toilet paper. These are things that you don't really need to have but may instill a bit of comfort or familiarity during hard times.
Guns and ammunition
This is an item that many people think will be the backbone of any bartering system. More so the ammunition than the guns, but if you can get cheap guns they would make potential barter items for larger things. It may make sense to even collect ammunition for a gun you don't have, just be sure it's a common caliber gun.
Survival Skills Books
You shouldn't trade away your last book on survival skills but if you have several you may well be able to trade off some books to help other people survive. This may well be one of the most valuable items long term. If you can get other people to learn how to grow their own food they won't be trying to steal yours.
This can take the form of books, magazines, pamphlets, etc. While it's available the internet can supply a wealth of information but if there's not electricity you're not going to be able to surf the web, or even pull information off a computer or CD. Make sure you have printed out physical copies of anything you think you may need.
After a collapse
This is a very extensive list but it's by no means exhaustive. If people can no longer go to the store to get what they need they'll have to get it from somewhere. You probably wont be able to store everything that you will need or your situation will change causing you needs to change. In this case having some extra of something to trade with someone else who has what you need could faciliate you both getting what you need.
As you're storing up things for yourself simply pick up a couple extra to have available for barter. If it's something you'll use it will likely be something that someone else will use. And if you don't trade it for something you'll have it to use yourself.