US Ebay Motors FTW mate .
You could also try Findapart, Victorian MC Wreckers or Metropolitan Spares in Sydney. Findapart is a great service, you should be able to track down a 2nd-hand tensioner through them......
and I think it's actually the balance-shaft tensioner which has broken......the alternator on those bikes is a normal alternator that is bolted onto the end of the crank and sits on the l/h side of the motor - the little chain that sits out in front of the clutch runs to a balance-shaft, and is know to cause problems on these bikes....
