I have over many years purchased a lot of items at very low prices and resold them on ebay and other forums. That is how I raised enough money to purchase the gear I now have. So when I spotted this deal I jumped on it knowing what it's worth and what I could sell it for. When the seller said he needed rent money by today and had put it on craigslist Sunday morning early, I was the first to respond. When I first spoke to him I was not convinced it was legit but some things he told me and the way he said them made me a little less skeptical. He said he was a student and bought the camera for a advertising class where they were learning to photograph water droplets. That seemed like something that one would not make up, but maybe he's a clever thief or I'm an easy target. Anyway now my doubts are resurfacing and you are probably right about not reselling it but now if I keep it and it needs service I may have trouble. I wish I could find out from Canon without devulging my identity and run the risk of the camera being confiscated from me. I would never knowingly buy stolen items with the intent on reselling them for a profit.
This is a public record admitting your concerns that it might be stolen. Contact your local police immediately! Losing the money you have spent on the camera will be the least of your worries if you are later found to be in possession of stolen merchandise. Selling it now without checking would be even worse. Good luck.