You can get 7970s. I think they use 200 watts/each so you need to multiply 200(number of GPU's) + like 150 watts to spare. Try to go for the most efficient PSU's to save electricty.
Mine pulls about 210W from the wall @ 1100MHz core, 950MHz memory and 260W from the wall @ 969MHz core, 1700MHz memory (scrypt).
Just FYI.
Unfortunately my budget is limited. Its either 2x7870xt or 1x7970.
Now I am browsing for 7970 with unlocked voltages, any suggestions? Seems Gigabyte is locked.
It seems like some of the Gigabyte cards can hit higher hash rates than the rest. I have a Sapphire hashing at 660Mh/s (660kh/s for LTC). Whatever you do, get one with a nice cooler. You don't want it running at 85C all day long.