After posting this I went and read this article which shows going a fresh install.

Considering it's just $70 for Win8 Pro I'd rather just buy the box so I can easily do a fresh install like this (I'm assuming the $70 retail box from Staples is not also an upgrade DVD). I don't want to install an older OS an a blank drive just so I can then wipe it out by doing a custom install and install Win8. That sounds rather clumsy.

The wording on the Staples website doesn't explain exactly what they're Win8 Pro boxed version is.