eBay, Craigslist, ect.
Local game shops might also have what you're looking for too if you have any of those (not Gamestop type stores, gaming stores).
Just be warned you're getting a used and possible refurshbished console so there's no warranty. I was worried my Xbox was going to die (and I wanted an HDMI port) so I just sold my old old 360 and bought an Arcade. All I had to do was transfer my hard drive and I was all set.








