Stole this from Neogaf and it only works if you have Amazon prime.
Get a free 2 month subscription for Audible on Groupon.
Activate it and sign in to your Amazon account on the audible website.
You should get an email for $25 free Amazon credit.
Got the game for $10.
Thanks for this. I didn't use the credit on Final Fantasy, but used it to get Rise of the Tomb Raider for $5.