When you load the menu option, the values you see displayed will be the values currently in use by your game. Vanilla values are 3.3 and 2.0. If the menu is displaying different values, then you have a mod installed which is already adjusting these two settings. If you choose to select a new setting, Trade & Barter will override the settings from the other mod. If at any time you wish to revert the settings back to those made by another mod, simply deselect this setting and reload your game. You will need to reload your game before the changes from Trade & Barter are fully canceled out.
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.

I wish I came up with this fantastic idea. SharedEarth is a free site that connects landowners with gardeners and farmers in need of space to grow crops (i.e. starting a home vegetable garden). You can find free access to land in exchange for sharing a little bit of produce with the landowner. In a time of a strong and growing local food movement and concerns about food safety, SharedEarth might just be the most important sharing site of all!

However, this isn’t always possible. For instance, you may have a $150 digital music player and want a small refrigerator worth $100. In this case, if both parties are certain of what they want and understand the difference in value, there should be no barterer’s remorse. Alternatively, you can ask for the mini-fridge plus $50 to make the trade – the worst anyone can say is “no.”
He would have heard of channels and sandbanks, of natural features of the land useful for sea-marks, of villages and tribes and modes of barter and precautions to take: with the instructive tales about native chiefs dyed more or less blue, whose character for greediness, ferocity, or amiability must have been expounded to him with that capacity for vivid language which seems joined naturally to the shadiness of moral character and recklessness of disposition.