Looks like there is a school board using this seller in Alberta, mentioning the same discount you mention:
http://www.blackgold.ab.ca/Schools1/...ers/May_09.pdf
As is this BC school board:
Roberts Creek Community Elementary School
Looks legit to me, but if you can verify with Adobe as Thunderball said then that would be best. (but I think its OK).
Looking through the Ontario education software list, looks like CS4 Standard edition is free for Ontario schools. Will have to give this a look this upcoming Fall.
Good to see you are getting this software the proper way BTW!