So I'm playing the Earth 18 civs senario as the French. I send a great merchant all the way from Paris to Beijing on the other side of the world. I made 1500. I started a new game as the Egyptians. I sent a great merchant from Thebes to Perespolis and made the same amount although the distance must have been 1/4! There must be a limit of 1500 gold per mission. Has anyone else noticed this?