Apple does not allow BTC as a mode of payment yet (and I think they don't have any plans for this in near future). But to what I can suggest:

Go to Goods section here - https://bitcointalk.org/index.php?board=51.0
Post your request there and wait for someone to agree and sell for BTC.
Most important part - always go for a reputable escrow and save yourself from those scams taking place every to and fro.