A few things to keep in mind before bidding on an iPhone 3G from eBay:
1. You can no longer buy an unactivated iPhone.
2. The biggest iPhone will only run you US$299 (half of US$600 going rate).
3. Eventually, even your grandma will have an iPhone, and that means you will have paid over US$600 to have the same phone as your grandma. Remember the RAZR and the Macarena, people! [eBay]