Seasonic S12 600W Power Supply
 

There are a lot of expensive power supplies on the market but unfortunately most are expensive due to gimmicks like flashy LED fans, see through PSU containers and detachable cables. What you should look for instead is for a power supply that has passed industry certification (like nVIDIA's SLI certified PSUs) and do your homework by posting in computer forums asking the more experienced users what they think of certain models. This way you can get yourself a truly reliable power supply, not some pretty piece of junk.