Bro just pirate windows 7 64bit or something. i have literally never paid for an OS in my entire life. Use linux? shit i think win 10 was free maybe still is?
Support for Windows 7 ended on January 14, 2020 also you need don't to buy license key for windows 10 although some features may be limited. Inactivated versions of windows 10 have a watermark in the bottom right saying, “Activate Windows”. You also can't personalize any colors, themes, backgrounds, etc also there some guides / tools how you can get around it
Or you can buy a cheap key off ebay like 5 doller
I can also recommend get a SSD If you do not have one help to load stuff faster and use the old hard drive as storage
some countries are pricey on computer parts it could also due to having potato computer
I got secondary computer that got intel i5-750, 4 sticks of 2 GB DDR3 ram, MSI 7870 hawk 2GB, 120 GB SSD, 1 TB hard drive and windows 10 64bit, It run most game pretty fine from this site