I think linking ingame economy with real money is a potentially horrible idea.
for that to work you have to be 100percent sure that its balanced, fair, not abusible, etc., else you have had users for the longest time.
Its true that it kind of works for second life to incorporate real money, but the basic premise is totally different, as the money isn't directly linked to a game system (as second life basically has nothing like gameplay) but is just used for the same transactions people would make in real life, only in game. When people decide that ingame assets are worth enough that they actually start going to ebay for gold, than thats all fine and dandy and then is the time to think about how to use that value that people attached to game objects. But thats vastly different from actively trying to sell people stuff, or letting them earn money ingame.
The kind of system that actually could work, and was already mentioned, is (even if its a buzzword thats used an awful lot lately) Micropayments, like special ships, or real estate like in second life, or stuff like that. The problem is, you need people who are actually willing to spend real money on it, and you need to make it cool enough that they feel its worth it, but not too cool, else all the players who don't want to (or can) spend a lot of money (or any at all) in the game leave because all the cool stuff is only accessible for a fee anyways. And a playerbase is what an online game needs most. Thats also what an online game loses fastest if it makes only a small mistake, and orders of magnitudes faster if real money was involved in the mistake.
When linking real money with a game in a different way than paying to be able to play that game, you tread dangerous ground. Creating the next big thing and a 'real' virtual universe which people see as a sufficient alternative to real life that they consider investing money there, isn't very likely to happen.
Not to mention the potential legal issues arising, especially with the vastly different legal situations in many countries.
I don't say it cannot work, i just say its highly unlikely that you can set out to do something like that from the beginning. After all you want to make a game, not a living environment for gold farmers, whom you pay out of your own pockets.
PS: Eve is really the best example for a complex in-game economy. its also the best example for how to keep all but the most hardcore players out because its so freakin complex
Not to say it isn't cool, i would play it if its combat were more like wing commander or freelancer or jumpgate online, and not WoW in space.
PPS: my post may sound pretty negative, but im just very sceptic about that kind of thing, and you should be very very certain that you know what you're getting yourself into when you go in that direction. In my experience most players react very allergic when real money starts spilling into a gaming environment.
