While I believed Microsoft's guidance to Mac users was they would need to purchase the system builder version of Windows 8, it turns out this isn't necessarily the case.
Customers running a full version of Windows 7 (Windows 7 Full Packaged Product, or FPP) in a virtual machine environment that supports Windows 8 can buy the Windows 8 upgrade through electronic software download (ESD) or at retail and upgrade from Windows 7 to Windows 8. If you are using Parallels Desktop, there's step-by-step knowledge-base guidance as to how to upgrade to the final version of Windows 8 on Parallels' site.
Starting February 1, Microsoft is launching a new Windows 8 promotion for students only. The Windows 8 student offer will allow students to purchase the Windows 8 Pro upgrade edition online via the Microsoft Store for $69.99 (ERP).