In the same game as Gribol I have (income depends a lot on commerce bonus too)
2 Frankincense, all 4 sold, 24+26 can't see all boni in an easy way. Also the saving is not shown think its 11g -3g or so per for another 32, so 100g+ value
1 Iron, 4 all sold 44 gold directly. cost 8 missing cost, 3 if available so 4x5 saved.
1 Marble, 2 all sold 18g
1 Precious, 1 of 1 sold 16g
1 silk, no sales as none apparent need it, bonus ???
2 silver, 4 all sold 29+22g
This is turn 381 a meagre amount of emporiums .. maybe I did something wrong or they are really difficult to build.
I think Gribol might have managed this a bit better than me!
Though he has been as lucky as me that most he gets from exotic merchants ... are exotic fruits and Ivory or are those the exotic things that are not covered by Emporiums?
Its really difficult to get an total overview of goods, hence my other post about improving goods overview/maps.
Iron - can only deliver to ~60% of demand total, I think I build whenever I can, unless loyalty is low.
Also don't think I have seen a precious mine ... and searching doesn't help here as I got an emporium.

- MyPrecious.JPG (88.86 KiB) Viewed 1100 times
My emporium is the only source all over the map.
The only requirement is mining exploit and it appears on the list of buildings but I don't think I have been able to select it yet.
And I found a new bug when you have/buys more than 10 goods!!! see other post.
And another one, counting wood, when there are 3 sources, see other post.