The general problem is, game authors tend to make the economy in which advances players will create tremendous amount of gold and goods. The more the level, the more the energy. The more the perk, the more goods or gold for one point of energy. Isn't it?

Well, good, balanced game should be more like a life. More advanced players can do more advanced things than beginners, not 100x more things ad day. Gold doesn't grow on trees. There's no computer tradesman that will buy everything you produce or any skin you will hunt in forest.

Have you considered to allow player guildes to emit their own currency? They would have to adapt it's number to the number of players. When they emit too much, it would inflate and nobody would buy it.

Doing good economy is very difficult, hovewer.