[DonRotolo]

I have nothing but high praise for the ShopBot stuff. The 48" wide BT48 Buddy PRSstandard is a good size at 24 x 48 (unlikely you'll need to cut larger than that), and they definitely offer discounts to schools. The software they bundle with it - Vectric Vcarve Pro and PartWorks 3D are both powerful and intuitive, and work with SolidWorks and Inventor quite well.

the Alpha series uses close loop motors, and you're unlikely to need that for a robotics team or school. Open-loop steppers are sufficient for anything but the production environment.

With the router provided you'll be able to cut Aluminum (or wood or plastic) with the correct bit. Not super fast, but fast enough. For aluminum you should consider a mist coolant system and a vacuum dust/chip management system.

If you go for the spindle option, you'll gain some flexibility (because the spindle can spin at slower speeds than the router) but not a lot more cutting power. For me personally I would opt for the router, but for a school getting the funding for a spindle afterwards might be more hassle that it is worth.

If you can, definitely take their training. You will absolutely have to teach 2 or 3 kids each year to run and maintain the machine, somewhat like a lathe or mill, it is a complex and sensitive machine requiring some skill and knowledge to avoid damage or injury. Their training goes into a lot of detail, giving you a foundation for student lessons.

Also, give the ShopBot folks a call. They are happy to talk machining and can steer you in the right direction.

I know you need to buy new, so I won't mention the various 'kits' out there, but for others who might not be limited, one can build a machine similar to the 48 Buddy Standard for about $5k, including software & computer. I recommend the KRMx02 (Google it).