It is zero. StartSSL has had free certs for years. Let's Encrypt will give another source of free certs. I expect shortly after that basic DV certs will be give

It is zero. StartSSL has had free certs for years. Let's Encrypt will give another source of free certs. I expect shortly after that basic DV certs will be given out for free from most CA's. But most people don't care about finite or not finite resources. I am starting to suspect that the isse is mostly just the cost (with not everyone yet knowing how to get free certs). If your main objection is that you don't like the StartSSL UI, you can get a paid DV very for $5. That is about half the price of your domain.