Smitexpert,
I have developed probably close to 100 custom CMS systems for customer deployments, when everything is equal they do not cost anymore than deploying an out of the box CMS system. Now the key to having a good custom CMS system is having someone that knows and understands how to deploy for the web. That is where the challenge lies.
Most, not all, younger web developers today have learned on Joomla, WordPress and the many IDE platforms that are out there and really do not understand how to code. They are use to dragging and dropping items on a screen and believe that is how they code a web site. They could not be farther from the truth. If anyone has really looked under the hood of a Dreamweaver website it is full of bloat and improper coding techniques. Now, I will admit, it has gotten better over the last few years, but it is still no where near as good as a good coder, oh and by the way, a good coder is faster and designs much better sites than most of the those IDEs also. In my opinion Dreamweaver was one of the worth things that ever happened to web development.
I have found that designers and developers that rely on products like Dreamweaver do not really understand the coding process and the need to streamline and optimize their code. Now Dreamweaver has its place, but it is a limited place in a good developers tool set. There is nothing that beats the knowledge of understanding the code you are reading, knowing how to maximize the performance of the code and minimize the footprint of the code on the site.
Learn to code and you will see what I mean about the out of the box CMS. One size fits all, is the farthest thing from the truth in the world of commercial web development. But as long as people keep that philosophy, of one size fits all, people like me will never run out of work. I am called to fix more problems with the out of the box solutions and then eventually move them to a custom system, then you can imagine.
What is the most interesting, I have had many people / businesses move from an Out of the Box CMS to a Custom System. I have never had anyone move from a custom system to an out of the box system .... that says something right there.
Put it to the real test.
Design two exact system, with a professional web developer.
Same page count, same content, same graphics, same mobile responsiveness, same SEO optimization, same security.
The custom site will always be faster, more responsive, have much better security and easier to maintain than the out of the box CMS.
As I have said in many posts, WordPress, Joomla and the many other CMS systems have a place, they are well designed and well written for their intended audience. But they are by no means an optimized CMS system. Trying to be all things to all people just does not allow that. Too many plug-ins, too many security holes, and way too much bloat for a serious business system.