If you’re interested in having a website which runs on OS X, having full control of the server with multiple fail-safes and redundencies, and a very large pipe to it, then you might want to consider the offerings from MacMiniColo.net.
These folks are part of a larger operation run by Switch Communications in Las Vegas, Nevada. Switch runs one of the biggest high-speed data centers in the country.
MacMiniColo specializes in running MacMini servers with OS X server. You can send them your MacMini, or buy one from them. The monthly costs start at $35, and go up from there depending on what add-on services you require.
While you can certainly get hosting packages for less then this, remember that your site will be the only one on your server. Also, these guys offer a very fat pipe to your server.
Check them out: http://www.macminicolo.net