Well, no.
The cost of the training has nothing to do with the fact that it is not worth to do crafting and the only thing you can do is mine for gold. Yes, you need money for training and yes, this amount is really high, but what I get out of your posts, is that changing the amount of money needed to train solves the economy issue. This doesn't work. Even if training would cost only a tria per level, everybody would still need tria to buy stuff (or at least something valuable to sell, which is the same economy-wise) and you would still use the fastest method to get something valuable, which would be mining for gold.
If we have a near balanced economy (or at least somewhat near), than adjusting how fast you can level is another issue. A balanced economy would mean: as long as you do something sensible, you get a good amount of money/training material out of it, if you invest some time. Of course there can be differences, but not that some technically important parts don't make sense to do, becaus you don't get any value out of it.
short:
We have two issues:
Balancing economy
and
Adjusting the amount of time to level up in skills and stats
Of course the the amount of time is related to the economy, but it isn't depending on HOW you get the ressources out of a balanced economy (mining, fighting, crafting)
@tadill:
Yes, moving the economy in the hand of the players is an option and then the regulation would be in the hand of some thinking merchants. Parts of the economy are still fixed in NPCs and can't be changed by players.