They should have it like in the game Sacred where you can trade runes usually at 4-1 ratio.
As what usually happens the Magic users get Might runes and the Warrior gets Mind runes.
I hope in the Expansion pack that they can do something like this.
Since as is now you can only rely on blind luck to find the type and quanity you need.
Also Runes for quest rewards would imo, be much better than gold.
GB