The cost of the upgrade was revealed yesterday by Paul Thurrott, a popular blogger who writes SuperSite for Windows.
An earlier report by CNET had claimed that Microsoft would charge a fee for the upgrade, but had not spelled out the amount. CNET said that the program would kick off alongside the delivery of Windows 8 Release Preview.
Microsoft has said it will ship the preview the first week of June. If the company follows the same schedule it used in 2009 to deliver Windows 7's release candidate, the most likely date is Tuesday, June 5.
Eligible customers must purchase a new Windows 7-powered PC between June 2012 and January 2013.