What are the advantages? First and most noticeable unique front end with and extra built in functionality, features and customization options. Keep in mind that many professional WordPress themes designed to address specific niches and have extra plugins like booking, calendar synchronization, e commerce, forums and others. As these themes designed by professionals, they are usually better coded plus they get regular updates to insure there compatibility with the latest WordPress version, and popular plugins. Premium themes offer higher quality and need to be purchased. Average price for professional WordPress theme is around $50-$80 per one license for one web site.