Custom Catalogs are created to offer any items not part of the ARI supplied catalogs and accessories. Creating a custom catalog allows you the opportunity to sell these items on your website and allows your customer the opportunity to add it to their cart for checkout and payment.
Custom catalogs are not to be confused with Custom Pages, which are just additional special pages you can create on your website not automatically offered via the WSS Pro template program. Custom pages do not offer the option to purchase anything from your site. An example of a custom page would be showcasing your service department with pictures and a description of their daily operations.