I've thought about this one, too. I think the answer is that you don't need YC at all. If you have no money, just bootstrap.

On the other hand, applying costs nothing but a little bit of time and it pushes you to clarify your thinking about your venture. So, I think you might as well apply, but I wouldn't invest that much time or effort into it. Spend your time building your business instead. If you make your customers happy, investors will find you.