From 9to5Toys.com:

Update: You are too late for Best Buy but Walmart has that beat with 20% off $50 iTunes gift cards.

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Today only, Best Buy offers the $100 iTunes gift card for $85 with free shipping (which will arrive before Christmas) or in-store pickup.  iTunes gift cards are good for music, videos, movies, iBooks, Mac and iOS Apps and much more.

Note: Sam’s Club has a $25 4-pack for $84.64 with free shipping for delivery before Christmas.