On your next visit to Barnes & Noble, check out the sheet music books. There's a good chance you find it in at least one of the books.
If there is a music shop somewhat near you, they may have it either singly or in a book.
Another less expensive alternative is probably an online sheet music store. Usually a search for "[title of song] sheet music" will turn up some pretty good results. I can't really say which of these online stores are best, however, as I don't have any experience with any of them. Some offer instant transposing to a different key and MIDI versions as well.