+ 2003: OzFormers booth/stall at Sydney SupaNova and Animania conventions
+ 2004: OzFormers stall at Sydney Animania convention. Sabretron convention at Ashfield Sydney.
+ 2006: OzToyCon at King St Wharf, Sydney.
+ 2009: OTCA stall at SMASH! convention, Sydney.
In short, these convention booths/stalls and conventions weren't profitable and just aren't worth running. American conventions have backing from Hasbro - and also America has a larger fan base due to the larger population there... we don't. A user here called SilverfromOz was thinking about organising an Australian convention with support from Hasbro, but I have no idea how that's going. Basically without support from Hasbro, it's just not really viable.
Anyway, here are some photos:
OzFormers 2003 (@ Sydney SupaNova)
Sabretron 2004 (Australia's first full Transformers convention)
OzToyCon (Australia's second and last full TF con)
OTCA stall @ SMASH! 2009
P.S.: It's not only in America - Cybertron-Con is a Hasbro-sanctioned convention in China. There are also other non-sanctioned conventions in the U.S., UK, Sweden, Germany, Denmark, the Netherlands, Japan, the Phillipines and Canada. Some are more successful than others.
P.P.S.: There are various toy collector fairs around that a lot of TF fans regularly go to, like the Parramatta Fair in Sydney, the Sandown Fair in Melbourne, the Nexus Fair in Perth etc etc.