Some advanced features/intigrations(ie ecommerce, email marketing integration, cookie notice, sticky header, side panel popups, embedded Instagram, and so forth) can cost extra as require additional third party plugins to function.  Of course we would let you know of options and pricing and request approval prior to integration if something comes up.  We prefer and always try to use free plugins if available.  Sometimes the path to least expenses result though is to buy the plugin.  🙂