At Coinstar kiosks, exchange $20 or more in coins and opt for an Amazon gift card (instead of cash) and you'll receive a $5 Amazon MP3 credit for free. Even better, by choosing an Amazon gift card, the Coinstar transaction fee is waived. The MP3 code will be printed on the bottom of your Coinstar receipt, redeem it here. That's the best such deal we've seen from Coinstar and Amazon. Deal ends September 23 and the MP3 credit expires October 31.