Windows 8 Pro Upgrade: $40

Perhaps worried about adoption rates, this new price point would make the OS much more available for those sitting on the fence. Assuming of course, they’d get over the lack of a Start Button.

The upgrade price is valid for any Windows XP, Windows Vista, and Windows 7 machine in a stated 131 markets. If you want a hard copy, you’ll have to pay an extra $15 (plus S&H) for Microsoft to mail you one or buy it at retail for $70.

Source:
Microsoft