now now, though in general, the idea holds true, just because its too good to be true doesn't ALWAYS mean that it is. I got a first generation iphone with AppleCare for $160 off of craigslist!
As long as you deal locally and are able to see the item upfront before payment, I'd say its worth a shot.
I got my Pomeranian off of craigslist last year, my 6k worth of diamonds engagement ring that we got for 700, I sold 2 phones (Nokia and my Storm) and bought a first gen iPhone a few weeks ago.. not all are bad.. I love craigslist.. But that add is VERY sketchy.. veer away! veer away!