I need ideas for a gift!?

a friend of mine is turning 18 and i really need to find an amazing present for him, i would like to spend around 200€ (i'm italian! that's about 250/300$) or less. He already has a great mobile and ipod.. i'm looking for something really peculiar.. he's some kind of a nerd guy, loves apple and harry potter.. but it doesn't have to be related to them. i just want the present to be absolutely amusing and surprising! give me any idea! thanks so much ^^