MinecraftEdu is also beta testing what looks to be a really cool set of modified tools for educators. From their site: "Our custom MinecraftEdu mod was created by teachers, for teachers. It works right on top of the original Minecraft game and is designed for classroom use. We've lowered the barriers so that ANY teacher can benefit from this amazing game." There will be both institutional and personal versions available.
The aim is to make it accessible for anyone who wants to use Minecraft in an educational setting to get up and running, affordably and easily, even if they aren't big Minecraft experts at the beginning. It's a great idea, and I'll be interested to check out the mod once it's released. In the meantime, that discount is legit - definitely worth it.