SOME SUGGESTIONS - With all these different variables, you may be wondering what the best settings are to achieve a good balance in your game. Of course this will depend on what you want. Many people (myself included) like to make trade more difficult. I also like to set the barter settings relatively close to de-emphasize Speech skill and place more importance on the Speech perks.
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.
Fluctuating Gold - This option will add an additional random amount of gold to merchant inventories so that merchants don't always have a static amount of gold. This will be added to their base gold, so they will always have at least the base amount available. The random amounts have been set with regard to the vanilla gold amount and won't increase merchant gold drastically above the vanilla amounts.
Trading goods and services without the use of money is called bartering. Early civilizations relied on this kind of exchange. Even cultures in modern society rely on it. Think of people in prison who commonly trade cigarettes for protection or extra food. For the most part, they don't have cash. So, like people in pre-currency economies, they work with what they have.
Since the 1830s, direct barter in western market economies has been aided by exchanges which frequently utilize alternative currencies based on the labor theory of value, and designed to prevent profit taking by intermediators. Examples include the Owenite socialists, the Cincinnati Time store, and more recently Ithaca HOURS (Time banking) and the LETS system.