I'm a university professor, and there's no way i can afford personally 1$/month per student. And definitely the school won't allow me the budget. "Use the lab computers", they'll say.. So I don't know how realistically someone can use repl.it for teaching, at least in public/higher education.

Repl.it allows each teacher account to have up to 200 students for free! Is this enough to cover all your students? If not, reach out to me at tim@repl.it and we can work something out.