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.
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.)
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." 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. 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. 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.
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.
Identify your resources. What items do you have that you could easily part with? Use a critical eye to go through your home, and consider possessions you may have in storage or that another family member or friend is currently using. If you would prefer to offer services, honestly assess what you could provide for others that they would otherwise pay a professional to do. It could be a skill or a talent or hobby such as photography.