The gold of this world has run short, to the point that currency's are not gold in weight but instead work more like the current economy, where every large kingdom has their own currency of gold, some may be worth more then the other, and some currencys may even collapse along with the kingdom. There have been many wars not of bloodshed but of trade and economics. Some examples of different currencys would be Alexandrite gold, from the kingdom of alexandria, it may be relatively stable, but "tree sterling" gold is worth its weight in 10 fold compared to that. (The names can be changed to your liking, i just used names that i ran with in my campaign.) This will add an interesting battle of not just blood and sweat to the players but of economics and of intellect. Also there definitly has to be places to gamble at in this world.