The standard for run of the mill dressage lessons froma decently qualified instructor go up to about $40/hr. For a very good dressage instructor whom has ridden internationally expect to pay around $75/45mins without travel, or trailer in fees. ($ in CAN)
$65 is very reasonable for a highly qualified instructor. I don't know what your dressage experience is or how motivated you are, but generally I find that as long as you know your way around a horse and know something about dressage then going for the very good instructor versus the $25/hr instructor is very well worth the money. When you are paying $75, you are paying for the person's knowledge on how to get a horse in and out of any situation. With the less experienced person, you are paying to be a "guinea pig" in some situations.
I've also never heard of this specific trainer. Make sure you first go watch some lessons and see if her language skills are good and if she can actually teach in a style you can learn from.