Windows Canada announced that you can reserve a packaged DVD of the upgrade to Windows 8 Pro for $69.99 via participating retailers. From the hardware it runs on, to the UI, to the apps that people download through the Windows Store, Windows 8 is the biggest change to Windows since Windows 95.
If you want to wait until general availability on October 26th you will be able to upgrade online via Windows.com using the Windows 8 Upgrade Assistant for just $39.99. If you purchase (or have purchased) an eligible Windows 7 PC anytime between June 2, 2012 and January 31, 2013 you will be able to purchase an upgrade to Windows 8 Pro for only $14.99 which will be redeemable starting October 26th.