In his analysis of barter between coastal and inland villages in the Trobriand Islands, Keith Hart highlighted the difference between highly ceremonial gift exchange between community leaders, and the barter that occurs between individual households. The haggling that takes place between strangers is possible because of the larger temporary political order established by the gift exchanges of leaders. From this he concludes that barter is "an atomized interaction predicated upon the presence of society" (i.e. that social order established by gift exchange), and not typical between complete strangers.
LOCATION - Prices are lower in smaller towns, but merchants also can't afford to pay you top septim for your goods. Cities are expensive, but there is more money to be made there. Merchants in cities charge higher prices when selling their wares, but they are also willing to pay more for premium goods in order to make sure that their shops stay well-stocked. The five major cities can now have their buying and selling rates set individually to reflect their size, wealth, access to supply and shipping routes, or status as a trading center.
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.