Official dates have been posted as well as prices. More info here:
http://bgr.com/2015/06/02/windows-10-prices-free-reservation/

Quote
Microsoft on Monday told CNET that Windows 10 will cost just as much as its predecessor. That means prices for Windows 10 will run anywhere from $110 for the Windows 10 Home package to $199 for the Windows 10 Pro edition. Additionally a Windows 10 Pro Pack will let users upgrade from Home to Pro for $99.

Windows 10 will ship on July 29th, the company confirmed, meaning that the free update program will expire precisely on July 29th, 2016. Depending on the version of Windows 7 or Windows 8 you have, you?ll be able to update your computer for free to Windows 10 Mobile, Home or Pro.

Sandeep Luthra | LTMedical.net
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