The same thing holds true of all other possessions; for barter, in general, had its original beginning in nature, some men having a surplus, others too little of what was necessary for them: hence it is evident, that the selling provisions for money is not according to the natural use of things; for they were obliged to use barter for those things which they wanted; but it is plain that barter could have no place in the first, that is to say, in family society; but must have begun when the number of those who composed the community was enlarged: for the first of these had all things in common; but when they came to be separated they were obliged to exchange with each other many different things which both parties wanted.
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.
Other countries, though, do not have the reporting requirement that the U.S. does concerning proceeds from barter transactions, but taxation is handled the same way as a cash transaction. If one barters for a profit, one pays the appropriate tax; if one generates a loss in the transaction, they have a loss. Bartering for business is also taxed accordingly as business income or business expense. Many barter exchanges require that one register as a business.