You can't find 7950's right now, and if you can they are over $500 bucks a piece.
Not intending to thread hijack here, but if this actually is the case I've got a Sapphire 7950 3GB DDR5 975mhz core 1300mhz memclock card that I'd be willing to sell. Especially if the price is in that sort of range
The card is still under warranty, was purchased in march 2013 has mined, but never continuously for long periods, has also never been overclock and never ran hotter than 69*C