I am currently running 2x Sapphire 5830's.
Picked them up at NewEgg for 102$
I have mine overclocked a bit, running at 1000Core and 300Mem. I am averaging 311Mhash/s. Thats pushing it a little bit on Stock voltages, but I haven't had an issue with the system becoming unstable or hardlocks.
Running @ 975/300 would using Phoenix miner, would get you right about on that 300mhash/s mark. Which if you ask me, is bad ass for a 100 Dollar card.
i run mine 996/900 and get 300 on phoenix, mine hate having their mem lowered for some reason, so i just run like i posted. very good cards for the money imo