What will Diablo 3 RMT prices be?
Well, most players, even if they put most of what they find into the $-AH, will make almost no money. If any at all. Some hardcore players will make a few dollars. Some really hardcore players will make a few hundred dollars.
But only some lucky players will make a thousand and more. You will not be one of them.
At all time there will be many items on the $-AH that go for $20-$80. If not, all market research of microtransaction companies has been wrong. It will be interesting to find out whether they were right. I think they could ask more than just $80 for a monocle.
Now, if Blizzard is serious about the amount of revenue they make with fees, they will do everything they can to prevent those 5% of the players, who are willing to pay money, from running out of reasons to do so.
There are two ways to accomplish this: Either some items are incredibly rare, or we get WoW-like tiers of items.
"Incredibly rare" items means so rare, that your chance to find one is so small that it is safe to assume that you will never find one, no matter how much you play. Therefore, the only players to ever own one are the ones who really spend massive amounts of money on the game. And after they did this, they stop spending money.
Now, Blizzard will argue that it is not fair that the best items go only to the richest player. What they really think, of course, is that they don't want the richest players to only ever buy an item once. And so we will get a tiered system like WoW.
With a tiered system the richest players will be encouraged to buy the best items again and again every few months! And it's even more fair, is it not? See how RMT is not just a business model, but changes the game ?
About immersion and stuff. I really don't find this kind of $-AH as bad as normal microtransactions. To know that every item has a history inside the game is just great. Sure, it's much worse than a game in which characters got what they have due to in-game actions. But if you really desperately want RMT, do it this way.
What I don't really understand is how Blizzard expects to get through with this legally. Fact of the matter is that playing Diablo 3 will be as difficult as using a slot machine. And if you're lucky you can get a lot of money that less lucky players put into the machine. .. That's gambling ..