The support that YC provides is definitely more valuable than the money they provide. With that being said, however, you can't discount the benefit of having that extra cash. $5,000 for 5% equity essentially valuates your company at $100,000. Ask yourself, would anybody outright pay that much for what you have built? On top of that, YC also provides an additional $5000 to cover living expenses. Thats a deal if I've ever seen one.