Variable Merchant Gold - Adds more gold to select merchants. Merchants in major cities will no longer have the same amount of gold as their small-town counterparts. There are three levels with increasingly greater difference between the gold amounts for city & small town merchants. Personally, I would recommend leaving the Base Merchant Gold at vanilla values and choosing one of the Variable settings instead. You can stack the Variable settings by selecting multiple options in order to get even greater increases in merchant gold, but I really don't recommend doing this as I haven't balanced the values with this intention.
This mod alters the "VendorGold..." leveled lists that determine merchant base gold. It also alters the "PerkInvestor..." leveled lists. If you are using any other mod that alters these leveled lists then you will need to decide whether to load it before or after Trade & Barter. If Trade & Barter is loaded last, then it will overwrite any changes made by other mods to these leveled lists. If the leveled list changes from Trade & Barter get overwritten, then the merchant gold options & the "Inventory Changes when Invested" will likely not work.
Anthropologists have argued, in contrast, "that when something resembling barter does occur in stateless societies it is almost always between strangers, people who would otherwise be enemies."[6] Barter occurred between strangers, not fellow villagers, and hence cannot be used to naturalisticly explain the origin of money without the state. Since most people engaged in trade knew each other, exchange was fostered through the extension of credit.[4][7] Marcel Mauss, author of 'The Gift', argued that the first economic contracts were to not act in one's economic self-interest, and that before money, exchange was fostered through the processes of reciprocity and redistribution, not barter.[8] Everyday exchange relations in such societies are characterized by generalized reciprocity, or a non-calculative familial "communism" where each takes according to their needs, and gives as they have.[9]

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.

Freegans are people who embrace community and sharing, in opposition to a society based on materialism and greed. Freegans avoid purchasing new products or food as much as possible. Instead, they spend a lot of time digging through trash and waste, looking for the things they need. Yes, it’s an extreme example of sharing and bartering, but they make the system work for them! 

Though trade and bartering are both methods that have been used for the purpose of obtaining required goods and services over the years, there is some difference between barter and trade. That is, while bartering involves the exchange of one product for another, trade involves exchanging money for goods. Trade is also conducted in commodities, currencies, stocks, etc. Trade and bartering may sound similar but there are a number of important differences between barter and trade. It is important to clearly understand each concept in order to grasp their similarities and differences. The following article offers a detailed overview of each and highlights their similarities and differences.
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]