There’s Aikido of WS. I was emailing Pam about her classes for kids, but we wound up not being able to afford it. It’s a $90/month flat rate for kids and you can go 1-3 times/week.
Integrated Martial Arts on Fauntleroy & Genesse. 1 day a week class until they turn 7 years old. Then they go to 2 days a week. It is a much smaller class and the instructors are great!