think not, you are effectively boosting the AI's ability to pump out mage troops, also as I noted you can only sell to them when they have less than 50 crystals (or so).
Sincerely ~ Kongdej
Ythril may not be able to makes mages
But they can make some very nivce guardian statues - You sell them the rope ....
It's still a very good trade in your favor. The AI can pump out as many mage troops as it wants...but with the gold you've obtained, you've juggernauted your heroes that will easily dispatch their mage troops.
Now I'm not saying there is necessarily a problem with the trade ratio. I'm saying there is a problem with troop weakness and hero strength.
Also, agreed, different factions should value resources differently, depending on the strategy they are trying to achieve.
AI should also have the ability to adapt their primary strategy if their resource base doesn't warrent it's strength. This should change their trade values to coincide with there new agenda.