How Much do you spend MONTHLY on your kids extracurricular activities?

I have two kids. I spend $90 per month on her dance classes. Strictly for fun. They're not competing or doing any recitals. My son has been wanting to do Muay Thai for about a year and I finally let him do a trial class at a place he really likes. They didn't tell us the price upfront but after the class. He does get three more trial class but the price seemed a little high to me. $400 sign up , which includes equipment and first month. Then $200 monthly. I did some research and that seems to be the best Muay Thai studio in the area so the price seems to reflect that. I just don't want to spend money unnecessarily (I have a habit of doing that). So how much do you dish out monthly for your kids activities?