There is no reason to have any cost on respec. The only restrictions should be on when and where you can do it (e.g. only in town and while not in combat)
If you dont want people changing their skills too often then put a time restriction on it, like once per day. Giving it a exponentially rising cost is stupid. It means that if I dont like the way I built my character I only have two options, grind for hours to get the gold to change it, or just go play somthing else. A lot of people are going to choose that second option, especially single player rpg fans that arent into MMOs, which I expect ESO wants to attract a lot of.
The developers and fans are kidding themselves if they think a game can be successful by catering to MMO players alone. The one true MMO success story came from a game that attracted a large number of fans from its massivly popular single player franchise, most of which had never played an MMO in their life, and ESO is in a position to do the same. Lame, grindy MMO mechanics like stupidly high respec costs may work for the MMO vets like the people on this forum, but those Elder Scrolls fans who make this there first MMO are going to avoid the hastle by canceling their subscription and going back to waiting for ES6.
MMO's, more than any other game genre, will get the response of "I dont play those games" from peopel you talk to. Its mechanics like this that put up that barrier. No MMO will succeede without breaking that barrier down.