My son's college uses this for their engineering classes, all students are required to have one.
http://www.digilentinc.com/Products/Detail.cfm?NavPath=2,842,1018&Prod=ANALOG-DISCOVERY&CFID=4560016&CFTOKEN=67122c2f7f893c33-0719A872-5056-0201-02A88D8690FA9B7F
Pretty sure you can do a lot with it at high school level robotics.