Some are very expensive, but this site uses Joomla which is an amazing product and happens to be free.  It is also one of my favourite CMSs.

Depending on your knowledge of IT you may need to spend money installing a Content Management System on your website or even spend a little getting someone to teach you how to use it, but it is really no harder to use than Microsoft Office. You may also end up spending money getting someone to build you a template or themes appropriate to your company.

If you don't know enough about Content Management Systems you can also end up paying someone a fortune to build you a CMS that does the same thing as a free opensource CMS so sometimes it is worth talking to an expert who will probably charge you a lot less for his or her knowledge. Sometimes you do need a bespoke product. These usually cost a lot to develop. Sometimes you don't need a CMS at all. The skill is knowing what you need.