i don't know how much i'd trust those companies though, if you plan to buy from one of them, make sure you plug their names into www.resellerratings.com and check up on them.
A lot of colleges have special licencing that allows them to churn out copies of some MS products (Windows, VisualStudio, etc) for students for next to nothing. Some places charge $5 a CD. Some places set up a download site where, if you provide the time & a CD, you can burn it for free.