It's an odd debate, and I really dont think theres any clear answer. I have worked for a private tutoring college for 6 years now as a casual tutor and it still marvels me at the prices the college charges, and the variance in quality and experience of teachers. The college charges a standard rate of around $60 per hour for private tutoring (although most students are preferred to have a shared lesson (2 students) at 2/3 of the price each).
I believe the teachers are all of a high standard, however, their experience can range from 2nd year uni students with high HSC marks, to ex school teachers, all at the same rate.
In this case you are paying for reputation, professionalism, and for a receipt!
Personally, I like to keep tutoring affordable. My main aim is to build the confidence of students, as well as their skills and problem solving abilities. For me, I charge $40/hr but I do have my own facilities if they prefer to go somewhere outside of their own home. I've also had almost 6 years experience in HSC tutoring and could easily call on many of my ex students for glowing references. The pricing is not to make alot of money, but to justify the time spent.
Also, just cos someone got awesome results in their own HSC, doesnt mean theyre any good at explaining the techniques to someone else...