How much does it cost for my 5 year old grandson to take lessons once a week during the week days?

This center very often cancel the class or change. And they don't refund.

Hello SC, Thank you for your interest in lessons for your grandson. The first step is to schedule a free evaluation lesson so we can work with him and determine what class type is best to start with. After we do that, we will work with you to find a schedule that works for you. The prices for the different classes are listed here. https://www.swimrightacademy.com/west-los-angeles/ We usually love group classes for 5 year olds! Thanks again

My son is in private lessons (about $125)

Depends if you want to do group or private lessons