Go to this link once you are signed in to Amazon to see if you're eligible:
http://www.amazon.com/b/?_encoding=UTF8&camp=1789&creative=390957&linkCode=ur2&node=10713131011&tag=cl03f-20If you're eligible, you'll see this:
Enjoy this exclusive Gift Cards offer for Prime members: Surprise someone with an Amazon.com Gift Card, and get a $5 promotional code to spend on yourself. Just purchase at least $25 in Amazon.com Gift Cards by January 31, 2015, and we'll email you a $5 promotional code to spend at Amazon.com. Enter "JAN25PRIME" at checkout to qualify. A perfect present for any occasion, Amazon.com Gift Cards can be sent via email, printed at home, or sent through the mail (with Free One-Day Shipping). Amazon.com Gift Cards are redeemable storewide for millions of items and never expire. Learn how to use your promotional code. Terms and conditions apply; learn more.
Important Notification: This offer is valid ONLY to eligible customers. To qualify, you must: (1) purchase the Amazon.com Gift Cards using the Amazon.com account to which you are currently logged in; and (2) enter the promotional code "JAN25PRIME" in the "Gift Cards & Promotional Codes" box when you check out. Additional Terms and Conditions apply.
If you're not eligible, you'll see this:
Thank you for your interest in Amazon.com Gift Cards.
Unfortunately, you are not eligible for this offer.
(I'm not sure whether it's available for all Prime members, or only targeted to some of them)