The Consumerist have a great piece up detailing the "confessions" of a serial Craigslist reseller. Beginning his "job" with the launch of the PS3, the guy has since sold loads of PS3s and Wiis, all to crazy profits and all thanks to some questionable ideas on fairness and the exploiting of an open market.
The Wiis have been a steady stream of income. I'm a casual video game player but I got to know the guy who runs my local Gamestop. He told me when they get their deliveries and said Wii's were first come, first serve. Since the summer I've bought 10 of them and sold them for an average of 150 bucks over cost.
In all he's sold 5 PS3s, each for between a $300-500 profit, and 10 Wiis, each for at least a $150 profit. Head on over to The Consumerist for the full rundown. It'll make your skin crawl, but if you like reading books on serial killers or puppy kickers it should be roughly the same kind of deal.