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While I also thought the headline promised a more thorough analysis including time & money saved by virtue of better security, I am getting the sense from the few posts here that maybe most folks don't feel comfortable using craigslist or ebay to buy computer equipment.
I bought my very first Mac laptop for $650 in late 2000 and sold it in mid 2002 for $600, bundled with a peripheral item that I paid $100 for. I then upgraded to a new Mac laptop and felt great that I had paid out a mere $150 for my intro. to the Mac OS and almost two years of continuous use. I have since bought and sold other macs and mac gear using craigslist. While I am less inclined to consider dealing in these items through ebay, I'll admit I have browsed at the possibility of buying an iPhone from an ebay seller local enough to perhaps consider a face to face deal.
Plus I thought everyone (at least in the SF Bay area) knew that perhaps the best time to look for Mac gear on craigslist is just after the new stuff gets announced at Macworld. Gotta love those early adopters.