Are private universities worth the money?

I want to get a masters in education to teach. My bachelors is in psych, so I am not currently certified to teach. There is a private university near me that offers a program for masters+ teacher license, but it will cost at least $40,000. There is a state school that offers the same thing for half that. The private school program is designed to only take a year & a half if I start this summer. So, if I pay more I can be teaching by 2012-13 school year. However the state school would be a year later. Any suggestions? I am torn between cheap & lengthy or expensive & quick...