[Wetzel]

Mindstorms and the Carnegie Mellon Curriculum or Vex and Swept Away. I've taught a 6 week summer school class around the former, and am teaching a two week class this summer around the later. The Legos keep, until sets get mixed up or pieces lost to the vacuum, but that is a slow and minor degradation of ability. The Vex will last as long or shorter, depending on how much you let your students cut the material. One feedback I've gotten from a PLTW engineering teacher who has used both FTC and VEX was that the students all preferred FTC because it wasn't so open ended, that the LEGOs were easier to deal with. YMMV

There is a classroom bundle from Vex for about $6k that gets you a field, a game, and kits for 5 robots. Getting enough so that they can work in groups of 3 or 4 makes a huge difference when hands are engaged. I'd take these rather than one big machine for a classroom.

Wetzel