[Q]

Please correct me if I am wrong but I believe that starfury generates randomly the sell and buy costs of commodities on the base of the initial component value.
Therefore it will not be possibly to make profits bigger on a percent base but only the absolute values as SJ pointed out.
I use commodities only as a additional income: I choose first my jobs and then check if by chance there is a profit to be made at the same time/trip by available commodities.