The Eve economy isn't 100% free CCP (the game developers) can adjust how much ISK (the in game currency) is created, by adjusting mission rewards and bounties on NPC ships. They also control how much money is taken out by regulating taxes in NPC stations and how and how much minerals are distributed in asteroids witch every other item is made from. Luckily there is no intensive for them to abuse that power and they make more money by keeping the system stable so players have fun.
Thou the economy is mostly controlled by the players there is still some inflation but over all i think its a pretty good model, and eve over all could be a model of the world if governments disappeared yesterday.
Also if you are playing eve i recommend looking in to margin trading, in the long term it`s the best way to earn ISK.