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.
It is estimated that over 450,000 businesses in the United States were involved in barter exchange activities in 2010. There are approximately 400 commercial and corporate barter companies serving all parts of the world. There are many opportunities for entrepreneurs to start a barter exchange. Several major cities in the U.S. and Canada do not currently have a local barter exchange. There are two industry groups in the United States, the National Association of Trade Exchanges (NATE) and the International Reciprocal Trade Association (IRTA). Both offer training and promote high ethical standards among their members. Moreover, each has created its own currency through which its member barter companies can trade. NATE's currency is the known as the BANC and IRTA's currency is called Universal Currency (UC).[citation needed] In Canada, the largest barter exchange is Tradebank, founded in 1987. In the United States, the largest barter exchange and corporate trade group is International Monetary Systems, founded in 1985, now with representation in various countries. In Australia and New Zealand the largest barter exchange is Bartercard, founded in 1991, with offices in the United Kingdom,United States, Cyprus,UAE and Thailand.[citation needed] 

On paper, this sounds a bit like delayed barter, but it bears some significant differences. For one thing, it’s much more efficient than Smith’s idea of a barter system, since it doesn’t depend on each person simultaneously having what the other wants. It’s also not tit for tat: No one ever assigns a specific value to the meat or cake or house-building labor, meaning debts can’t be transferred.
As Orlove noted, barter may occur in commercial economies, usually during periods of monetary crisis. During such a crisis, currency may be in short supply, or highly devalued through hyperinflation. In such cases, money ceases to be the universal medium of exchange or standard of value. Money may be in such short supply that it becomes an item of barter itself rather than the means of exchange. Barter may also occur when people cannot afford to keep money (as when hyperinflation quickly devalues it).[15]
In England, about 30 to 40 cooperative societies sent their surplus goods to an "exchange bazaar" for direct barter in London, which later adopted a similar labour note. The British Association for Promoting Cooperative Knowledge established an "equitable labour exchange" in 1830. This was expanded as the National Equitable Labour Exchange in 1832 on Grays Inn Road in London.[21] These efforts became the basis of the British cooperative movement of the 1840s. In 1848, the socialist and first self-designated anarchist Pierre-Joseph Proudhon postulated a system of time chits. In 1875, Karl Marx wrote of "Labor Certificates" (Arbeitszertifikaten) in his Critique of the Gotha Program of a "certificate from society that [the labourer] has furnished such and such an amount of labour", which can be used to draw "from the social stock of means of consumption as much as costs the same amount of labour."[22]
Put a price tag on it. Successful bartering must result in the satisfaction of both parties. This can only happen if the items bartered are realistically valued. If you have an item you would like to trade, obtain an accurate appraisal. An item is only worth what someone is willing to pay for it. Therefore, do your research and look at the "selling" section on eBay to find out what online buyers have paid for similar items.
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.
Other anthropologists have questioned whether barter is typically between "total" strangers, a form of barter known as "silent trade". Silent trade, also called silent barter, dumb barter ("dumb" here used in its old meaning of "mute"), or depot trade, is a method by which traders who cannot speak each other's language can trade without talking. However, Benjamin Orlove has shown that while barter occurs through "silent trade" (between strangers), it also occurs in commercial markets as well. "Because barter is a difficult way of conducting trade, it will occur only where there are strong institutional constraints on the use of money or where the barter symbolically denotes a special social relationship and is used in well-defined conditions. To sum up, multipurpose money in markets is like lubrication for machines - necessary for the most efficient function, but not necessary for the existence of the market itself."[13]