WordPress.com starts at the nice round figure of free, with premium features typically costing in at a few dollars a month. You don't get anything like the flexibility of your own private instance, but if your need is close to the core, it's a very easy experience.
WP Engine starts out at $49 a month, gives you far greater access to plugins etc, and offers some very nice features such as a staging environment to try out changes.
Finally, some commodity hosts do a great job in delivering WordPress installations that give you the bare minimum of admin. This link on WordPress.org lists a few they recommend, or you can scan the forums, starting here.