How do I purchase the music on my wish list? I can't seem to find a buy button??

There used to be a 'buy all' button on the wish list screen, but for some reason that has been removed on the current version of iTunes. You will need to buy each item individually, there should be a 'buy' button to the right of each.

If you'd like the 'buy all' button to be brought back then you could try leaving feedbackd for Apple and maybe it'll be added back in a future update : http://www.apple.com/feedback/ipad.html