First of all, it’s free and open to all. WordPress is an open source Content Management System based on PHP. So you don’t need to pay someone to setup a WordPress site on your server.
You will get so many premium WordPress Themes at low cost to make an attractive website. You can buy it from Themeforest which is the leading marketplace for selling themes or you can buy from my website where you will get free support. If I ignore the server cost then this is the only cost to set up a WordPress site on your server. Also, you can install free themes but you didn’t get support from there.
There are so many Content management systems like WordPress but those are not so easy to handle. In WordPress you can manage your website on your own.
WordPress repository is vast. You can get so many plugins to maintain and boost up your business for free.