The future is here from Microsoft, come get it for $16.19! My experience so far.
http://www.windowsupgradeoffer.com/en-US
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$16.19 for a valid, legitimate copy of Microsoft Windows 8? All you need is a valid Windows 7 product key from a recently new computer. MS will then email a promo code too use at the Windows 8 Pro upgrade checkout. We have performed four Windows 7 to 8 upgrades at the time of writing this and all upgrades went off with out any problems.
Windows 8 performs a strict compatibility check, which on my diagnostic machine meant un-installing my Android adb drivers before the upgrade process could begin, we were also alerted too a few apps, like UltraISO, that needed a update. The upgrade literally takes minutes to install, retaining all user accounts and settings. For those who have Windows 8 RTM installed on machines, we were able to activate Windows 8 RTM using the upgrade product key.
So, if you want a fresh install, toss in the RTM release, format, and activate with key you purchased for $16.19 and enjoy If you with to purchase more product keys at the discounted price you must run the upgrade assistant on a Windows 7 or older machine, running the upgrade assistant executable in Windows 8 will not work and from I have seen there is NO webpage too purchase the product key at.