When your company's business requirements have expanded beyond the scope of what many of the open source CMS platforms can provide you will have sufficient revenue to pay to have a custom solution done properly.
A open source CMS platform is a custom site. there are 1,000 of templates to choose from: as an end point or a beginning. There are thousands of extensions and modules to choose form: to augment and supplement.
Our production team uses Joomla for clients from $30k/yr to $50 million/year of gross revenue. We are able to leverage the underlying programming to create custom sales and marketing applications. We can bridge to and integrate almost any other online program. For many, like SugarCRM and QuickBooks there are pre-existing bridges -- and for other clients we are able to craft unique solutions, all while saving hundreds of thousands by leveraging the open-source CMS platform as the framework.
I know that teams that are proficient in drupal, and even Wordpress will report the same.
My recommendation is that you personalizing the out-of-the-box paid-addons which are "exactly what is needed" and put more money into marketing/advertising!