Bigger ssd, better monitor, more ram, better quality PSU, a CPU that is just as good (especially since you can't overclock the cpu you chose on the board you choose, and it's less money by a bit
Yes, if you choose you can save money, not buy windows at all right now, download it and create an install file on your own USB with a different computer (from Microsoft's site) and install it that way. You can run it for a while on a trial basis and then buy a licence from them later. Or buy a CD version today and use that code when you install via USB