The reason you got such a good deal is because you have 200 influence. The more influence you have, the better deal you can get.
The REAL exploit is that if you have something like 50+ influence and the person you are trading with has no influence, this grants you a good "exchange rate" both ways and to continually commit arbitrage until all your opponent's resources are in your hands.
For example, I may be allowed to trade 1 crystal for 4 metal. Then I could trade 2 metal for 1 crystal. Rinse and repeat until you have all your opponent's resources and made him/her declare war on everyone else....for nothing. I'm surprised no one has mentioned this yet as it was the first thing I found out on Beta 4. I guess I should have said something earlier.
