If you need a replacement adapter to charge your iPhone, iPad, or iPod, we recommend getting an Apple USB power adapter. For a limited time, you can purchase one Apple USB power adapter at a special price — $10 USD or approximate equivalent in local currency. To qualify, you must turn in at least one USB power adapter and bring your iPhone, iPad, or iPod to an Apple Retail Store or participating Apple Authorized Service Provider for serial number validation. The special pricing on Apple USB power adapters is limited to one adapter for each iPhone, iPad, and iPod you own and is valid until October 18, 2013.
You can trade in any 3rd-party power adapter for a genuine Apple one. This is well worth doing.