CertSimple will be shutting down on January 30 2020. Read the announcement here.
A 'www' subdomain is free!
Just submit the 'plain' domain name without the www. We'll add a 'www' version to the certificate on our end, automatically, for free.
Note if you need more than one www - for example, you're registering many seperate domains - you'll have add and pay for the additional names.