Do you know what he currently has? There are some noice canceling headphones in the $50 range (granted they are not as good as the $350 ones, but they are better then $2 earbuds). If he's into crosswords or soduku to kill the time on flights there are electronic versions of both of those easily in that price range.

If he doesn't have an MP3 player, you can get some in that range, again it won't be an Ipod, but it will play music.