Not sure if it still available in Austraila, but I use a Halon 5lb extinguisher. After my expireneces in the Navy with other various for of extinguishers, I've found Halon to be the best for me.
No residue, contamination, etc.
This is a tight subject with people so I would check it out thoroughly in your local.
1st place I would start would be the local Fire Department. In the states, some departments even offer them at a discounted price.
71 250 Coupe
92 400E Sedan
90 944/S2 Cabriolet