mid-15c., apparently from Old French barater "to barter, cheat, deceive, haggle" (also, "to have sexual intercourse"), 12c., of uncertain origin, perhaps from a Celtic language (cf. Irish brath "treachery"). Connection between "trading" and "cheating" exists in several languages. Related: Bartered; bartering. The noun is first recorded 1590s, from the verb.

In his analysis of barter between coastal and inland villages in the Trobriand Islands, Keith Hart highlighted the difference between highly ceremonial gift exchange between community leaders, and the barter that occurs between individual households. The haggling that takes place between strangers is possible because of the larger temporary political order established by the gift exchanges of leaders. From this he concludes that barter is "an atomized interaction predicated upon the presence of society" (i.e. that social order established by gift exchange), and not typical between complete strangers.[14]
Especially prior to the Christmas holiday season, a gift and craft exchange can take the pinch out of your budget. Contact people within your network and arrange a day where people exchange homemade holiday decorations. You may not find everything you’re looking for, but you will likely find at least a few stocking stuffers – and the perfect price.
In recent years, barter has enjoyed a resurgence as a means of countering economic insecurity, unemployment and worker exploitation. The nature of modern-day work, the pervasiveness of the Internet and the rise of social networking have all contributed to its spread. Other examples of alternative economic systems include gift economies, sharing economies and time banks.
Barter is the process of trading products, goods or services, for other products, goods or services. It is a simple method of transaction, frequently one in which no money is exchanged. Barter systems are often utilized between nations, and sometimes between a nation and a corporation. Barter also occurs between corporations or companies and other businesses, and sometimes between a business and an individual, or two individuals. In the United States, billions of dollars worth of goods and services are exchanged each year through bartering.
Can you teach a skill like canning or cooking from scratch?  Food staples will be more readily available than the processed food many are used to buying at the grocery store and fast food.  And although many in the preparedness community know how to can and cook from scratch, your common everyday American doesn’t.  They wouldn’t know what to do with flour, eggs, and a little oil.
“Economic theory has always got to be historically bounded,” Beggs says. “I think it’s a mistake to think you’ll find the workings of modern money by going back to the origins of money.” He does point out that, while barter may not have been widespread, it’s possible that it happened somewhere and led to money, just given how much is unknown about such a large period of time.

So as you consider items to stockpile, you should think about items that are necessary, but might not take up a lot of space.  Referring back to Mark Goodwin’s book mentioned above, one thing the main characters looked for were canning lids and rings.  They don’t take up a lot of space and in a real collapse situation, they will be really worth it!
It’s hard to answer that without actually seeing a modern gift economy in action. Luckily, modern gift economies actually do exist. On a small scale, they exist among friends, who might lend each other a vacuum or a cup of flour. There’s even an example of a gift economy on a much larger scale, albeit one that’s not always in operation: The Rainbow Gathering, an annual festival in which about 10,000 people gather for a month in the woods (it rotates among various national forests around the country each year) and agree not to bring any money. Groups of attendees set up “kitchens,” in which they prepare and serve food for thousands of people every day, all for free. Classical economists might guess that people would take advantage of such a system, but, sure enough, everyone is fed, and the people who don’t cook play music, set up trails, teach classes, gather firewood, and perform in plays, among other things.
Zipcar has been renting cars by the hour or day for years now, and they keep adding to their list of participating cities. You can pay different membership and rental rates, depending on how frequently you think you’ll need a Zipcar. Though the process varies, you basically sign up in your city, pay the application fee of $25 and any annual fees (ranging from $0 to $60, depending on the plan), and voila – you can now borrow a Zipcar for an hourly rate or daily charge. The rental includes gasoline, auto insurance, and 180 free miles, which is usually plenty.