You will have to up your budget for the power supply or forget the crossfire option. A quality psu will cost at least $80 and you will have to add shipping to that. Go with Antec, PC Power and Cooling, Corsair or SeaSonic. Don't skimp on the psu, if it dies, a cheap one will most likely take other components with it.
Heh, yeah. Don't that happening, which is why I decided to buy the Seasonic suggested above.