The Great Merchant can also build the 'Customs House' tile improvement that produces a lot of gold per turn. It helps to specialize one or more of your cities for gold production by placing the city in an area with a lot of gold-per-turn bonus tiles like Gold, Silver, or Gems, and then focus heavily on building things like Trading Posts and Markets. You can build tile and city improvements that generate gold per turn, like Trading Posts and Markets. One major source of income is your cities.
One is that you could be making more money, and the other is that you could be spending less.
