Materials for a robotics class of 30

[sanddrag]

I am running a robotics class of approximately 30 students (two sections actually) and I have the opportunity to submit a wish-list for materials for the class. This is a class run during the school day, and is not directly related to FIRST or any other structured competition (yet).

The budget is not yet known, so I am considering all options, from the cheap, to the somewhat expensive. I'm looking for class sets of things, as I like to have no more than two students working in a group. I have experience with the Parallax Basic Stamp robots, and the Lego NXT system. I would like to hear from other educators, or even students, what types of materials/activities are successful in your classrooms for hands-on learning. Kits that come with instructional materials and guides (like the Parallax products) are definitely a good thing.

Also, if anyone can recommend a good book that is relevant to robotics, I would like to consider a class set of some reading material as well.

Thanks.