text: I have never purchased a PS seperately but you should check out tiger direct. this is were I order all my parts and they pretty much have the best prices around (no I don't work for them) Here is a link to their 500 watt PS's http://www.tigerdirect.com/applications/category/category_slc.asp?CatId=1079&\nyou could also check out geeks.com I order from them if the price is betterhttp://www.geeks.com/