TBH I thought itunes used the new AAC format. But im not positive. There is another place you could get him a voucher for and that is
allofmp3.com. Their music is dirt cheap and albums generally cost about 30p. You can also download songs in about 5-6 different formats which is handy. I love this site and download all my music from here!
I use itunes too becuase I have an ipod so downloading stuff in mp3 format is no trouble and he could even use his music on a different media player. Last december I put about £30 ($60) into my account and have downloaded 20 albums and have alot of money left. They also do vouchers so you should be fine.
www.allofmp3.com
P.S. This is a russian site and when you first enter it you will have to press the english tab in the top left corner. Dont worry about it being a russian site because all their music is american and british. They also have all the latest albums.