What I’d charge for a group fitness class is usually determined by the following:
-Number of participants
-Location of the class and if it would change weekly/monthly/etc.
-The exercise props needed to safely and effectively train the participants
-The additional resources needed outside of the training itself (i.e. phone/email/text support or coaching, individual workouts for the participants to do on their own time, 1-on-1 meetings to review evolving goals/achievements, etc.)
With all that in mind (and possibly more depending on the instance) the price usually results in each person paying anywhere between $10-20/class.
I hope this helps!