Hi,
As suggested, you can use Windows 10 and opt in to Preview.
https://insider.windows.com/
Then:
http://pcpartpicker.com/p/ydXNCJ
That's $426 (after rebates reimbursed). People have said they overclocked the G3258 with this exact motherboard, though I didn't add a more expensive cooler.
I'd probably change a few parts, but basically I managed:
G3258 + GTX950 2GB + 8GB DDR3
That's going to run many games far better than the APU's above (though they assumed budget for Windows too).
If you're okay with the W10 setup (you act as a beta tester basically but it might be okay) then you can get a pretty kick-ass system.