Found this little bit of info from a while ago. Part of Amazons terms which basically gives you a free ride to scam whatever you want from Amazon marketplace sellers but not from Amazon in house sales. Basically you can get a refund weather you return the item or not. Think about that…
BookScouter – A price comparison engine type site for selling your books, basically it searches all the sites that buy the books and then comes back with a list of prices for your book(s) and then you sell your book to that merchant/shop/store etc. obviously each place will have its own rules/prices so its worth checking a few. Apparently the prices offered I have been told are quite good.
Why Amazon? A good question since many eBay sellers also sell on Amazon would you not get the same problems? The answer oddly is no. Amazon actually enforce a far stricter and fairer set of rules and actually listen and work through problems with both sellers and buyers instead of a load of canned pre-scripted replies. Amazons customer service is far, far beyond what it is on eBay. I have had refunds before instantly credited as gift cards and another/replacement item sent out all on Amazons tab. Its not hard to find tales of excellent service from Amazon reps. eBay is slowly trying to be Amazon just take a look at the listings and you will see it.
EDIT 24/12/12: Not even a day later stumble across this Amazon Representative Creates Holiday Discount in Response to Reddit Comment see they do actually listen and follow through with promises.