I am the person that will be helping you today.
It will be a whole lot cheaper, if he purchases it through At&t's upgrade plan. Being that you will be doing the upgrade through AT&T, an Apple gift card would not work in your case. Information regarding AT&T gift cards are found on the following page: http://www.att.com/esupport/article.jsp?sid=KB99342&cv=820
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Thank you again, - Jason