When now the idea with trading system has been on for like some months, it's time to take this idea "serious";
The only thing why snk don't make the trading system is because it will "ruin" iEra's economy. And of course, I agree.
But if every Graalian had to pay for a trade, or a "trade card", then they still would get in money for the trading system.
If you're going to trade your ak47 for 2 Uzi's (for example), you would have to purschase a trading card. This trading card could only do one trade.
If you are going to trade more you would have to buy more cards, or maybe also an card that last longer.
Sorry for my bad english, if you got any questions, or didn't understand; I will try to answer them under here!