I'm upgrading to an iPhone 4 from my original, four-year-old model and I'm not sure what to do with the one I'm leaving behind. It's an 8GB phone that only works with Edge and won't take any of the new software upgrades, and the battery lasts barely a day with typical use. I don't know why anyone would want to buy it when there will be so many used 3G models floating around. Is there any kind of market value for these, perhaps for parts? Should I just hang onto it as a toy?