I have checked at various places and they do not have a long firewire 800 cables in Singapore. Stocks take forever to arrive and I've been quoted $250 for one cable? Eventually, I found them online at this website:
http://www.firewire-1394.com/firewire-800-1394b-cables.htm
If you have experienced trouble with your FW connection and having to reset your back all the time, based on my experience so far, the cable I received is very stable and despite being coiled up in a bundle (I bought the 32ft cable), the connection works fine without having to restart the camera/back. I notice that the 32ft cable has been described as "triple shielded", so that may be the reason why the connection is better and has lesser interference.
If you are using a Hassy, you may need to use a pen knife to shave off the rubber housing on one end in order to fit the plug into the FW housing in the back.
They also have 800-400 cables so you do not have to use adapters with the new macbooks(which adds to the connection problems). I believe long 800-400 wires are even more rare than 800-800.....