Luisiana and Alaska Purchase Shipmens cost each 200 coins.
The USA paid 15M USD for Luisana and 7.2M USD for Alsaka.
My suggestion for a historical relation: How about to chang the Shipment costs to 1500 coins for Luisiana and 720 coins for Alaska?
The prices are also reasonable for two 1.5 resource trickles.
Greetings from GER