I wonder what the value of Southern Cotton at a Union Trading Post would have been? Who would have set the exchange rate? Certainly not the Southern planter. Or do you think so? Would the southern planter have recieved fair market value for his product under such a system of trade?
Under the examples I have seen the answer to those questions would be NO! That is the reason the 'cotton buyers' were called 'speculators'. Buy low, and sale high was their trade. The lower they bought the goods for the more profit they made. And they paid for the privelege of being a cotton buyer for the Union Army, otherwise their goods were confiscated as being an unlicensed trader. Those trader licenses were very valuable, like an vacant Illinois Senate seat. That is where the local area army commanders that issued those licenses came into the picture.
Quite a little racket they had going on.