Im not sure if anyone has mentioned this to date but through reading the list of suggestions, I had a thought on something which might be an idea to add. Im sure the idea could be tossed around a little.
Firstly, if you have multiple cities in Planeshift with different prices and economies, you could have a shop that buys and sells items between cities. In fact, you could somehow use that shop to offer quests so that if you courier the package to another city then you will be paid a small amount of money upon its delivery. These items could then be sold down to the individual shops and regulating prices within those cities.
The other idea is having an ingame noticeboard for jobs/quests/contracts where NPC\'s or Players can request others to do things. You could submit a request that if somebody makes you a sword then you will pay them $x ? If someone gives you 5 bars of gold, you\'ll pay them $x ? A player may come along and take the idea and then try to fulfill it. This allows players to create their own quests.