Hi FDev, at the moment a carrier can only buy or sell a given commodity you can't do both at the same time (at different prices obviously). This means you can't setup a flow for commodities across the galaxy. If you were to add the ability to do this carriers would become portable hubs of commerce and add to their value and gameplay options considerably.
Regards,
CMDR Shazroth
Regards,
CMDR Shazroth