There are NO good cheap psu's.
Buy only a quality psu. A cheap psu will not deliver advertised power, and can damage anything it is attached to if it fails.
Here is one list, sorted by quality tiers:http://www.eggxpert.com/forums/thread/323050.aspx
A GTX660 can run on as little as 430w, and the corsair CX430 is about as inexpensive as they come with decent quality.
But... if you want ultra settings, the graphics card should probably be better than a GTX660.