Barter is a system of trade in which one party exchanges products, goods and services in order to obtain required products, goods and services possessed by another. In a barter system, no money exchanges hands between the buyer and the seller. Instead, both parties to the sale determine how much of a product a fair trade for another product or service. Since people assign different worth to different products, a barter system makes it difficult to decide how much of an item needs to be offered for another for the transaction to become a fair trade. Barter system was largely used long ago before the world developed the concept of currency for the exchange of goods. Nevertheless, the barter system is still prevalent today among nations, corporations, companies, individuals and businesses. The barter system makes trade easier for countries that experience large volatility in currency conversion and for countries that do not have sufficient financial resources, but have large volumes of commodities that can be traded for other commodities.
Barter, the direct exchange of goods or services—without an intervening medium of exchange or money—either according to established rates of exchange or by bargaining. It is considered the oldest form of commerce. Barter is common among traditional societies, particularly in those communities with some developed form of market. Goods may be bartered within a group as well as between groups, although gift exchange probably accounts for most intragroup trade, particularly in small and relatively simple societies. Where barter and gift exchange coexist, the simple barter of ordinary household items or food is distinguished from ceremonial exchange (such as a potlatch), which serves purposes other than purely economic ones.
MERCHANT GOLD - Trade & Barter gives you the option to set higher base gold amounts for each of the different vendor types.If you have another mod that alters the "VendorGold" leveled lists then you will have to decide if you wish to load Trade & Barter before or after the other mod. In most cases, I would recommend loading Trade & Barter after the other mod to take advantage of the flexibility and options provided by Trade & Barter. However, some mods, such as Economics of Skyrim, should be loaded AFTER Trade & Barter, so that this mod does not overwrite their changes. 

Barter is a system of exchange by which goods or services are directly exchanged for other goods or services without using a medium of exchange, such as money.[1] It is distinguishable from gift economies in that the reciprocal exchange is immediate and not delayed in time. It is usually bilateral, but may be multilateral (i.e., mediated through barter organizations) and usually exists parallel to monetary systems in most developed countries, though to a very limited extent. Barter usually replaces money as the method of exchange in times of monetary crisis, such as when the currency may be either unstable (e.g., hyperinflation or deflationary spiral) or simply unavailable for conducting commerce. 

Bartering is based on a simple concept: Two individuals negotiate to determine the relative value of their goods and services and offer them to one another in an even exchange. It is the oldest form of commerce, dating back to at time before hard currency even existed. (Learn more about how bartering evolved, read The History of Money: From Barter To Banknotes.)
The Internet provides a new medium for the barter exchange industry.  Pure Internet-based barter companies differ from traditional, organized trade exchanges in that they do not have a physical office. In modern Internet barter exchanges, there is an agreement or process in place to value goods and services exchanged, which is facilitated by the barter exchange for a fee. A barter exchange functions primarily as the organizer of a marketplace where members buy and sell products and services among themselves.
By default this option is turned off. When you load the mod menu, the value you see displayed is the setting currently in use in your game. The vanilla value is 2.0, so any other number indicates that another mod is already changing this setting. If you decide to turn this option on, than the settings from Trade & Barter will overwrite any changes to this value made by other mods. If at any time you wish to revert the settings back to those made by another mod, simply toggle off this option and reload your game. You will need to reload your game before the changes from Trade & Barter are fully canceled out.