Alternatives:
Many robotics teams have 501c3 nonprofit booster clubs. That org can receive the free software. It is exactly the same approach that Autodesk and Dassault use to provide their software to teams. There are many other benefits of having a 501c3, aside from free software. More info at
http://thinktank.wpi.edu/article/105
Alternately, you could buy licenses under the school's enterprise agreement for much cheaper than the retail price.
Many schools have programs that provide inexpensive licenses to employees/students.
Finally, if you know someone who works for Microsoft, if you politely ask they might buy you licenses from the company store and donate them.
DareDad, there are many paths for consumers to upgrade to free win10.
http://windows.microsoft.com/en-us/windows-10/about has details.