Im not sure what quality 1kW PSU you can get for $150. But yeah, also, just because you CAN do it, doesn't mean you should. The issue will be (at least for those of us in warm climates), the first hot day, playing BF4 or similar, temperature derating and overclocked gear. Or, in a couple of...
TDP of 780Ti is what 250W? Thats without overclock. So that Id say 600W required (derated), then add the 130W CPU and other components, Id say 750W PSU is cutting it too fine. My 580SLI system previously pulled 900W from the wall overclocked so I would say you'd want a 1kW PSU to be safe...