[@Wernher] Currently everyones currency has different valuea to each nation, C.E. seeming to be the most (so they convert their money to galactic credits). Example being... C.E. pays #50 for a missle from Alfhedil, USV pays $95 because their currency is worth less, most minor nations possibly  worth even less. C.E. has money to burn, so they can widely invest in a galactic credit. It's helpful to poor nations too. 

It's easy for you, buy and sell with your currency, and you get back AGR credits