School websites are your window to the world, there are many platforms out there, some paid, some free. The key to which is the right one, is more to do with what one is maintainable by your current workforce. Many of the paid solutions can be complicated to work with, and come with many restrictions although the design of the site is usually top drawer.
Free solutions such as WordPress, or Joomla can be used to create some truly fantastic sites, and with the right training can be edited by anybody. The complications come with free solutions when you start to create custom code, or move away from the norm.