The going rate should be what people are willing to pay.
A friend had to take a physics class and he had to get an A in the class or his chances of getting into the medical school of his choice would be shot. One slight problem- the only physics course available during the summer was calculus based and he never took calculus.
Now tell me- after spending thousands and sweating through a few years of pre med and maintaining a 4.0 GPA in relevant courses- how much would you be willing to pay me per hour for a crash course in calculus? $100 per hour? $200 per hour?
(I didn’t charge him since he was a friend but he took the sessions as serious as if he was paying a few hundred per hour. He got an A and into the school of his choice. He’s also a Dr. now.)