Hello, I have a bit of experience with SSLs in another environment. Here's what I know about shared SSL.
Shared SSL is not recommended for e-commerce sites, because customers expect to see your domain in the URL. And if you attempt to use your domain name with the shared certificate, it is not guaranteed to work. Even if visitors can see your site, the shared SSL warnings will make customers uncomfortable submitting their credit card information through your website
If you require an SSL solution, you should purchase one that is issued just to your domain. Your hosting provider will be happy to sell you one and they most likely will install it for you also.
There are all price points and security available - you need to define why you need one, and then compare pricing and features before buying. Just do a search for SSL and you will learn a lot.
Hope this helps a bit.
Just another abantecart user.