Any specific brand? Any idea what mh/s I could expect? Price?
Avoid anything by Powercolor, and any other vendor should be fine (MSI, Gigabyte, Diamond, etc I've found, anecdotally).
Should be able to hit 580MH/s without too much sweating, and upwards of 600MH/s if you start pushing it.
A 7970, for comparison, will get you 675MH/s with basic overclocking, and upwards of 700MH/s if you start pushing it. Most 7970's are stable @ ~685MH/s near 1130-35Mhz GPU overclocking, at an additional cost of near $100 USD.