I've seen systems that are worth hundreds and thousands of dollars fall to poor PSU choices. I've seen one PSU kill two motherboards in a row because they thought buying a flea market PSU was a good idea. I've seen video cards that cost $300 (USD) and more die because people thought their PSU would be enough to drive the GPU. You name it I've seen it. Including a $20 dollar 650 Watt PSU burn down part of a house. Computer PSU's aren't something to skimp on.
You can take your chances in the PSU crap shoot and go cheap, or you can buy a quality PSU like the Seasonic M12D 850 Watt Modular and know that you will enjoy a long safe computing experience. Keep in mind that cheap PSU might still be running but, PSU that are cheap don't provide good solid voltage so every time you push that button your shortening the life of your computer. Be smart, go with a good quality PSU from a manufacturer like Seasonic that will provide years of good service and keep that gaming shrine safe from the dreaded flea market PSU catastrophe.