Circuit Playground Purchase

Hi wonderful community!
I am doing the budget for next year. I will teach unit 6, but also more about physical computing by incorporating, Arduino, Raspeberry Pi and Microbit.

I have a total of 64 students in 4 sections, in 8th grade next year. What would be your ideal amount of equipment? I was thinking that in each class I have 15 to 18 students, so maybe buying 22 Adafruit and the other boards as well is a nice number to start with?
I was thinking on getting those kits on Amazon, but if I you can share with me some advice on how to make a smart purchase I would really appreciate it.
I am in Wilmington, Delaware. Private school.
Thank you so much!.