Here's a couple of good options for you. You'll need a high quality power supply, 550 watt for the 380X and 650 watts for the 390.
http://pcpartpicker.com/parts/compare/powercolor-video-card-vxr93908gbd5dhe,sapphire-video-card-100383ntocl/
UPDATE: The 390 is $259.99 after rebate but is currently sold out.