I don't think the price is too much of a big deal. When you think of what you get in retrospect, the cost is really cheap. For the price of about one movie, two video rentals, etc, you get a month of entertainment.
Of course, you have to take into account how much the developers are putting back into the game. I've never played FFXI, but WoW (World of Warcraft) the developers were always adding to the world. Many of these changes would have been considered expansions packs in games like Ultima Online. Just have to make sure you like the directiont eh developers are taking it, because they pretty much have complete control over your characters lives, and the hours you spent in the game.