The great thing about WordPress is the ability to add functionality easily. Using WordPress plugins allows third party plugins to be installed with ease. These plugins are mostly free.
If there are unique features that you want, you may have to pay for premium features. I personally think it is work paying for a plugin. It may give you the edge over your competitors or might just make your life a lot easier. Whatever the case may be the wide selection of plugins available are enormous. I always choose plugins that are widely used with a good track record.