Found something interesting @pedrosimao !!!
So in G Suite for business you can add other domain therefor other user@otherdomain.com
You can then name the new user as a superadmin, everybody can be superadmin so everybody can see if someone is ‘cheating’ (you can actually see the number of uploaded files, I don’t see any space usage). And you can also prepay the account!!! (minimum is 10€ so everyone would pay every 2 month)
I just tried with 2 unused domain, it works like a charm!
PM me if you want to give it a try