Illarion.org

Instead of the cost raising exponentially on the stat trainer, it would be a set amount that is fairly high but obtainable but you could only change 1 or 2 points every x days making it still restricted but not unbearable. A character's identity can change over time and being stuck into one stat set can feel very constraining. This would allow it to still be controllable so that people would have a hard time maximizing their stats to power gaming perfection if they were that elitist but still allow characters to change with time.

It does reach a maximum and all stat changes are that price from then onwards. The low priced early stat changes make the trainer accessible to everyone for a fair number of changes to the character build. I don't think there's a need to add a cool off to the trainer since it's really a money sink.