Using a third-party or counterfeit charger for your iPod, iPhone or iPad can be dangerous. Recently, there have been reports from China of one person being electrocuted and one being shocked and now in a coma by counterfeit or third-party chargers.
In response, Apple will now sell you one new, genuine charger for your Apple device for $10 (or the local equivalent outside the U.S.) in replacement for an existing charger, genuine or not, that you turn into them for disposal. (Apple is not going to make any attempt at the store to determine if your existing charger is a genuine Apple device, a counterfeit Apple device or a third-party device.)
For more information, click on this link.