Due to very scalable and dynamic structure with easily available plugins, the development in wordpress become very cost effective. The maintenance cost is also cheaper because you don't need to hire a person to update the content as you can easily manage it by yourself.
Most of the this module is ready in the wordpress as well as there are a lot of plugin available online for different purposes. So It take very small time to develop a site using wordpress.
Wordpress is easily manageable from background without having any technical knowledge.
Wordpress provides thousands of free plug-in and extensions which can used to build a beautiful website at lower cost.