Now, How much the price to buy or upgrade Windows 10 ?
As announce in microsoft windows blog that Windows 10 used in 300 million active device. The price to buy / upgrade windows 10 is $112 since the free offer of Windwos 10 upgrade was over in 29 July 2016.
But you can get the Windows 10 free if you buy the PC/desktop which is include Windows 10 inside. Some awesome notebook using Windows 10 include Microsoft surface are available in the market.
The newest is miBook from xiomi which use Windows 10 as operating system.