At Amazon, buy any combination of $50 in Amazon Gift Cards and you'll get a $10 Amazon Credit for free via coupon code "0815GCARDS". That's the best extra Amazon credit we've seen with an Amazon gift card purchase this year. (Previous Amazon credit offers have required Amazon Student, Amazon Prime, or purchases of $75+ multi-card packs.) The promotional credit will be be emailed to you after purchase and must be used by October 16.
You may not be eligible for this credit if you've previously received a similar promotion from Amazon.