Using shared SSL has its advantages insofar as saving about $50 on a dedicated IP and SSL certificate. But, it has its drawbacks. If you are running the Business License and maintaining client fan pages yourself, then shared SSL is fine - because you don't care that you have to log into WP Admin using the shared SSL "ugly" domain (not your own "pretty" domain).
If you use the shared SSL domain your hosting company provides, you would put that link in the WordPress settings for WordPress URL and Site URL. When you log in, you will have to go to https://sharedSslDomain.com/youraccount/yoursite/wp-admin. That works fine if you don't need a "pretty" brand domain.
But if you have the Enterprise License and are giving clients access to maintain their own fan pages, then you don't want them to have to log into https://sharedSslDomain.com/yourAccount/yoursite/wp-admin -- it is much more professional for them to log into https://yourPrettyDomain.com/wp-admin
I said all that to say this: consider the hours you may expend to work around getting a dedicated SSL. Consider the trade-off and cost of that time. Then consider that dedicated SSL can cost as little as $9 plus the const to install it.
I suggest you contact your web host and first ask if they will install external SSL certificates. If they will, then go to NameCheap.com and grab one for about $9 per year… If not, ask how much it costs to have them obtain and install an SSL Certificate for your domain name. It will give you a more professional business and will pay off in the long run.
One client = SSL costs + profit.
For the business you are trying to build, especially if you have the FanBuzz Enterprise License, I highly recommend that you consider getting a dedicated SSL for your domain. Then your customers will have a better user experience, you will have less support, and you will be able to build a brand.