Where to buy discs?

I teach at Forest Lawn High School, and we use the Disc Golf course frequently. I am a neophyte to this, and have been using Ultimate discs with my classes. They do not work very well, and they break too frequently. Does anyone know where I can purchase a class set (about 40) of multi-purpose discs? Feel free to e-mail me at teach821@hotmail.com.
Thanks.