Short tutorial on need for Static IP for SSL Certified Websites
Static IP is NOT MANDATORY For SSL Certified Websites.
Static IP is the permanent IP address assigned for the website by the internet service provider. Static IP is an exclusive address that is unique to your hosted server.
Almost all modern browsers do support Server Name Indication (SNI).
You could purchase a Static IP
It is not mandatory to purchase a Static IP for your website if you are having your hosting on shared space. Purchase if you want the above conditions to be statisfied.
VPS and Dedicated Hosting:
As a VPS and Decidated hosting service itself comes with a static IP, there is no need to purchase one. But, if you have several websites on your VPS or Dedicated hosting space the same IP will be reflected on all your websites. Hence, do decide if your SSL certified website require a Static IP and Purchase one.