• Do we have the time and technical expertise to setup the CMS ourselves?
• Does the CMS have a theme available that would meet our needs or are we capable of designing and building a theme for the CMS ourselves?
• Are we capable of building the site structure and migrating/creating the initial content for the site within the CMS?

Luckily, answering "No" to any of these questions doesn't mean it's the end of the road. Agencies like Soshal exist to support you in these areas and other parts of the process.