Hi there! Let's get back to basics for a bit.
Here is Broken Toy's opinion of developer-backed RMT.
I'm a little confused about his spouting commentary about Darwinism and that sort of thing, but the basic idea he has is that allowing people to buy fake money for your game from the developer unbalances your game's economy.
So, here's a simple question: what the hell is the difference between buying the money and killing a goblin for it?
The answer is: nothing! It's still just money in the system!
Sure, the dynamics change. Which players buy how much and how long it takes to gain money changes. But the basic balance does not: put money in, take money out.
Depending on your game, there's a zillion ways to take money out. Taxing purchases is one of my favorite: every time the player buys something in-game, the developer gets a cut and the seller gets the rest. Charging fake cash for skill learning, crafting, travel, and other in-game activities is also a valid idea, although it will probably piss off the poor players. You can charge money for owning land - a steep price, if the land is able to earn money by, say, being a shop or hosting tourneys or docking space ships. Thus, being a landowner makes you into a money sink.
These are largely adaptive systems. Sure, if someone comes in and brings $10,000 to the table, there's gonna be an in-game devaluation. But that devaluation isn't inflation. It's a bump. The currency gets spent on your money sinks and returns to a comfortable level of value, assuming you don't panic and drop real-world prices on your fake money.
This is true even if you provide a stipend to players (IE, 100 silver coins a week). You'll have to do some calculating and price adjusting based on how large other fonts are, but it's far from being a catastrophic, economy-ending event.
The only problem is if you put in both classic money fountains (like quests and goblin corpses) in addition to RMT. Then your RMT cost is going to have to reflect how quickly people can actually gather money in-game. That can get iffy. But it can still be managed.
Sometimes it feels good to get back to the basics for a while.