It would be difficult for someone else to tell you whether you should tip or not.  Yes, it is a personal preference.  But, beyond that, there are many different reasons for tipping.  Social norms (because you think it is expected or your friends tip), to reward an exceptional experience, to motivate an ATF or a new girl perhaps, to justify your own poor behavior, to bribe one to do something they would otherwise not do.  

I have had all of these types of tips offered to me and have accepted only one type...to reward me.   As in any service industry, tipping is wonderful when done in the proper spirit and to reward a job well done!!  The price of the goods has no bearing on whether to tip or not.

My .02 cents.
Hugs, Belinda

Regardless of her fee being above average or not, I would think you would only tip if you feel that what she did for you was so outstanding that her regular fee was inadequate.

Minnesota has been great with tipping to me....  I have received a few gifts, which to me is special compared to a few extra dollars....  I even received a gas card, which says Mr. X was paying attention to the fact that I still have a long way to tour...  A baseball signed by a Twin, once again paying attention to the fact that i enjoy sports...
My opinion if you wish to tip, I like gifts better.  Also, when Provider X calls for that ref. in a few weeks or a few months, I will remember exactly who you are...

Just my personal thoughts....

If I had a great time, sure I will tip. But if its average probablly not.