As i said before on another link.
Antec Earthwatts 500w or Corsair vx550Whttp://galaxy.pk/powersupply.htm
The EA500 ( if the sites specs are correct, 12V/17a = Seasonic ) is about 45% less the the EA500D Green
Oh, and it's enough power for either of the OP's graphics scenarios.
The 12V/17a [ if the specs are correct ] is actually dual rails with no OCP aka single rail, with 34 amps of output.
Even if the specs aren't correct and it's the first Delta model ( 12V/22a ) at around half the price of the Green model it's still a great deal, there's only a $2 difference at Newegg ( including shipping )