You probably ought to include the AMRA exhibition at the Surrey Dive in Box Hill. Every Labour Day weekend in March. I think there is one held in Chelsea or Carrum on the same weekend too, haven't seen anything to say it's still on this year. (all references Victorian, perhaps you should post to the Australian groups too).
You've just missed the Geelong weekend, it was the last weekend in January (same every year) at the hall next to Norlane Waterworld (Centenary Hall or something like that). AMRA is always on the Labour Day weekend as posted earlier. If you contact AMRA through
, you should get more info. I usually find the easiest way to get all the info on exhibitions and swap meets is to go to one in person and collect all the brochures. Usually you get every exhibition's details for the next year that way.
Not sure where you are located, but after I get to the next exhibition (probably AMRA, I'm not aware of another one before then and I'll probably dob myself in for our club's stand for a day or part thereof - British Railway Modellers of Australia -