I am sure you directed your question to the wrong forum. Try to find the telephone number of the club where the classes are held and ask there.
IDEA is the international Association of Fitness Professionals, and we will be happy to answer any question you have about fitness in general and in particular.
Good luck with your search, and have fun in your classes.
That’s a business question for you. $10/session is quite reasonable. But I agree with Karin, be sure that you are in compliance with the guidelines set by the facility where you are holding the classes.
If you are on your own, be a business-person and establish the rate that is most appropriate for you.