Sites That Sell Windows Keys/Licenses

Hi, Forgive me if this is not an appropriate place to ask such question, but I'm looking to purchase Windows 8 for my new system (in the process of building it), and a friend of mind pointed to several sites that sell activation keys cheaply, i.e. Keatingarts, mskeyoffer, getsoftwarekey, etc.. I am very skeptical of these websites to have any legitimacy, which, if I may say, look duplicate....