The following are on-line software distributors that sometimes provide software at discount rates and most of the time offer academic pricing.
Bizrate.com (best place to try first : comparison search of many other software sites)
Egghead.com
Macconnection.com
Onvia.com
AcademicSuperstore.com
Journeyed.com
Softwareshowcase.com
Campustech.com