With the Grand Final underway I thought I would go through the options if your in a location where you can't get Foxtel i.e. overseas.
The official and probably best quality way to watch is AFC TV which is the user pays official straming site for the AFC. With only one game left in the season it's not really great value to subscribe just for the grand final unless your interested in the other leagues on offer (China, Japan and Korea) and your in a location where your not geo blocked.
The other options are unofficial streams from My 2p (http://www.myp2p.eu/broadcast.php?matchid=108519&part=sports). The ones broadcasting using Veetle are pretty good quality if your connections good enough.
There is ABC grandstand who are doing a radio broadcast of the game available online at http://www.abc.net.au/radio/listenlive.htm
If your struggling internet connection wise you can follow a live blog with updates at http://www.theroar.com.au/2011/03/12/nerves-on-edge-for-a-league-decider/#comment-549083