Realcent.org

http://www.amazon.com/gp/help/customer/display.html?nodeId=1161240

So, if you sell PC items on Amazon, the fee is 6%, plus 99 cents.

You could cash your coins in at coinstar, get a amazon eCertificate with no percentage loss, then list a fictitious PC computer on amazon, buy it with your coinstar eCertificate. Reciev your cash with only a 6% loss.

Never sold anything on amazon, think this will work?

You could probably do better by selling your gift cards to one of those companies who buys gift cards or on ebay or craigslist or something like that. Or use your gift certificates to buy something that you could flip on ebay for less than that 6% loss.

But, no, I haven't tried the option that you've mentioned