Microsoft has today announced the prices for Windows 10 for those who are not eligible for a free upgrade. Windows 10 Home will cost you $110 USD and Windows 10 Pro will cost $199 USD. No prices have been released in any other currencies as of this point.
Windows 10 is due to be released on 29th July and will be free for anybody currently running a legit copy of Windows 7 or Windows 8. A preview build of Windows 10 is already available for anybody who wants to try it out now.