Using HTTPS / SSL with Domain Mapping and Multi Site

Hi there!

I run a Multi Site, with mapped domains. Each domain is controlled by the individual client via their own registrar. We create the site and map the domains. They move the nameservers and the site goes live.

Would it be the client's responsibility to purchase an SSL from their registrars? If so, would it work properly with a mapped domain? Or is there a way for me to give my clients a secure SSL globally that works for the whole multi site, without having to pay $100/yr per client?