Re:potjomkins village card question
I think that the Idea behind Potjomkin's village is that you pay only 2 rubles when buying it and when you trade it with BLUE trading card it's worth six Rubles.
1.Player buys Potjomkin's village for 2 rubles
2.Player Trades it with Bank(worth 13 Rubles) for 7 Rubles
So player pays 7 Rubles for exhanging the Potjomkin's village for the Bank.(13-6=7)