Going to Hawaii in a week, can I buy a pipe there and take it back on the plane?

You shouldn't have any problem carrying a pipe on the plane so long as you don't smoke out of it beforehand. If there's no resin in it then you can always say you plan to smoke tobacco out of it. But if you're not going to use it beforehand then you might as well just ship it with the bong. If I were you I'd just ship everything and make a pipe out of an apple while in Hawaii.