Off the top of my head a decent 500W unit will be more than enough for that card, you should be able to get something within your price range, just check that all the cabling works out in terms of connectors required etc. Nearly had a heart-attack when I ordered my PSU because of the price without checking if it had the required number of connectors for my GFX card.
Check the above-mentioned sites then read some reviews/opinions and you should be golden.
Personally I would shell out a little more if it meant I was getting a better PSU as imho its one component that tends to move with rigs and last quite a few years before needing to be replaced/upgraded.