Well honestly we think paying for things like name changes, character appearance changes, server transfers is fine. Even paying for a class change or paying for xp would be acceptable. The reason being you are guranteed any of those things if you just put in the time, you could always roll, start over on a different server and so on. You can even offer in-game items as long as the appearance only, although offering items that were orignaly promised exclusive for pre-orders etc would be wrong.
Now if you start offering things only availabe by paying real money or selling hard to get items, that's when you have problems. If you make someone pay to be able to use a certain set of items, that's basicly making everyone buy them if they want equal footing. If you sold raid gear that's unfair to those who had to raid months or years for their raid gear. And we are sure most of us have experienced a game(aoc gold) that started to sell gold for cash and how that destroyed the in-game economy.
Now getting rid of gold sellers is another issue that of course should be addressed. You could make the argument that an expansion is also something that forces people to buy it inAOC. aoc gold Although personnnaly we would say it's much more fair as your buying a huge chunck of content in which you still have to work for everything you gain. It's not nearly the slipper slope that micro-transactions are.
