Brian, I have bought Methyl B12 from Mr Vitamins in Chatswood.
http://www.mrvitamins.com.au. It is classified as 'Practitioner only' and is kept behind a counter. Manufacturer is Thorne (USA) and it is only available in 1000 microgram capsules. It is quite expensive. No idea of the quality.
I ordered methyl B12 from Iherb about a year ago but never received the goods - I assume they were confiscated by Aus customs. I am interested to hear more about people who have successfully purchased from Iherb as methyl B12 is much cheaper (per microgram) from them even with the delivery costs.
Martin