You'd have to change them whenever the commitete changed though
I doubt there is a free one which would let you have the @schoolname.com though as the domain is a saleable item. I remember there was one which had a variety of email endings once but I can't remember what it was now and I'm not sure it would let you have anything.
You could use a service like Freeparking to register the domain name, which would cost you around £5 per year. It comes with a very limited website (4 pages) but should be fine as a holding-page type thing... and unlimited POP3 e-mail. So each person could be assigned their own e-mail address person1@ person2@ etc, and use their own e-mail software, or web-based e-mail which collects from other pop3 accounts (such as GoogleMail).