I suppose it may have been discussed before, but I was wondering how to sell books as a package deal on Amazon.com, or elsewhere. For instance, if I had written a trilogy (which I plan on doing eventually) and wanted to sell all 3 books together as a package, perhaps for a discounted price, how would I do that? An example would be the Harry Potter box set books 1-7. (I was surprised to see that the boxed set gives an ISBN number. I suppose that they assign one to a whole set?). If anyone has actually done this, please let me know as I'm fairly ignorant. Also, has anyone actually done this?