caSaaS is a very inclusive service. We have conciously tried to avoid nickel-and-diming you with add-ons. All modules are always included, as are unlimited just about everything: sites, layouts, users, data lists, and so on. Therefore, expansion options are rarely needed and are limited to a very few.
In any version of caSaaS you may create as many sites as you would like. Adding one or more alternative domains to your service will add a dimension to that possibility.
Each caSaaS subscription comes with ample server/database space. In those exceptional cases where even more space is needed, you can add 2 GB at a time.
Likewise, a generous amount of data transfers is included with each subscription. If your website experiences huge demands, you may either pre-subscribe to a greater amount or elect to be billed monthly for actual excess transfers.
Any version of caSaaS lets you send up to 12,000 e-mails every month. You can subscribe to additional blocks of 12,000 if needed.