Website hosting can be free or cheap, but it's worth making a budget item for hosting with well-reviewed customer service and technical support. Some hosting companies offer reduced rates to non-profit organizations.
Registering your own domain name (http://yourchurchname.org) is relatively inexpensive and definitely worthwhile. Many hosting companies will handle the "paperwork" for you—but beware companies who register your domain in their name—be sure your congregation is the owner of record. Administration and Ownership Considerations offers some helpful advice for congregations regarding their websites.
WordPress is often included in hosting packages, and since that is an excellent option for creating a congregational website, look for a web host who offers and supports WordPress installations.
The UUA does not officially endorse any web hosting services, but the following have crossed our radar, mostly from the websters email list, whose members are always happy to offer additional reports of what's worked for them.