I'd check places like
www.overstock.com or even the major computer manufacturers... the most always have reconditioned equipment for a really good price... the reconditioned equipment also comes with some form of a warranty, so that when you get it home and it doesdn't turn on -- you are pretty much covered...
Otherwise, and it's be my least favorite place to go,because I am quite untrusting of the human race, is Ebay - -you might geta good deal there... but you also get what you pay for...