Path of Exile is an action RPG that promises to spark your interest in such games, especially if you are disappointed with Diablo III or Torchlight II. 

PoE has no currency that is used only for trading - every single item in the game has some intrinsic functionality and value. Thus, there are many items that are considered "currency items" in PoE - each does something different when consumed. 

Despite the multitude of currency items, historically one PoE currency always rose as the "gold standard" - completely through natural evolution. This is a fascinating free market model that has many similarities to real world barter based economies that evolved in situations where money was meaningless - for example due to inflation or banking collapse. Today the dominant currency is "orbs", with a few other types used for smaller trades so the market shifts as the game evolves. 

When new league begins in Path of Exile, when you decide to buy PoE currency, you should pick something which is necessary for you. 

There are quite a few divination cards in PoE that produce currency items, from wisdom scrolls all the way to mirror of kalandra. For the ones that can be exchanged for expensive items the pricing is very straightforward. The ones that require many cards to get average results are usually too cheap to trade for or bother with. 

Looking to break into the free to play Diablo style game, Path of Exile? If you've dipped your toes in and are looking to access some of the premium features like pets, weapon effects, and more but haven't felt the urge to drop cash - U4GM has a dealthat should help make supporting the game a little easier.