Why can you not buy another gift card or even transfer the balance to another user? You can do what you're suggesting and offer to buy something for someone and get it shipped directly to them though. Make a listing or move this thread to Services if so.
I don't know much about amazon.com, seriously, when I tried to buy another gift card it doesn't gives option to use the gift card balance in my account. And it can't be transferred to other user account too.
This is their policy:
http://www.amazon.com/gp/help/customer/display.html?nodeId=201138990Amazon.com Gift Cards can't be used to purchase other gift cards or applied to any order containing another gift card. You'll need to provide a credit card, debit card, or other valid payment method to pay for the order if you have gift cards in your Shopping Cart. Amazon.com Gift Cards can't be transferred to another account once the claim code has been redeemed. Amazon.com Gift Cards and Third-Party Gift Cards aren't returnable or refundable, except as required by law.
I'll move this thread to services. Thx