What power supply do you have? Include make, model, and wattage please
You are looking at a CPU and gpu upgrade (probably a Psu upgrade)
I5 4460 ($180)
Gtx 1070 ($379) (releases June 10th) or a used 980 ti (who knows how cheap? Maybe under $350)
If you need a new Psu-something 500w+ from Xfx, seasonic, or Evga ($50-$60)
[strike]And I'd add a 120gb ssd ($40)[/strike] already has