Joomla is open source, therefore free. Only hosting, the time to build it along with the training time is your startup cost. Ongoing, it will save your organization potentially tens of thousands of dollars, especially for a larger site that has a shopping cart and DB integration to internal systems, like accounting and inventory with web orders, seamlessly transferring from website to internal systems, etc.

Setup costs were about €2,000 in total. After setup there is not a day-to-day cost, everything is based on how much time you want to spent to update content.

Just plan properly. It will depend on your requirements. If you think Joomla can be used with the requirements you have, then proceed with it.

It is free, so no license has to be obtained. However, some addons can be bought. Keep in mind that for most commercial addons, there is also a free alternative existing (but without commercial support).

It's free.