the electronics are fine, the only restriction is nicotine juice, you can't sell it, but you can import it for personal use in up to 3 months worth of supply.
so maybe don't bring in more that 3 months supply of juice.
but whether you have to declare it or whatever, i have no idea. nic juice isn't taxed like tobacco.
maybe ring a government department, or read a few government websites, don't trust a forum on your future. you wouldn't want to be turned around at customs because some well meaning person gave you inaccurate or outdated advice.
and welcome to aus.
what state will you be in? and what will you be doing?
Liquid nicotine isn't sold here at all (no flavours can have any in it, no plain nic for vaping available).
We buy all our nic from China, USA or New Zealand. To my knowledge no one I know has had any problems buying 500ml of 100mg nic and getting it mailed here. Never been a problem buying a bunch of up to 24mg nic flavoured ejuice from various european/USA or Chinese sellers either.
So unless you are bringing 2 years worth of supply with you, I can't see any problems (besides the usual liquids and battery restrictions placed on passengers on passenger aircraft)
Hardware, batteries, 0mg nic flavoured juices etc are all sold openly, so zero problems buying vaping gear from vape shops or other retailers, or buying from overseas shops and getting them to mail it to you. No customs issues at all with gear.
just nicotine banned in autralia
For your airline info: Civil Aviation Safety Authority - eCigarettes and electronic cigarettes
Australia Custom on E-Cigarette:
Alcohol/Cig/Tobacco2
TGA:
Electronic cigarettes
Each importation for 3 month of usage is ok but this is a grey area. I have ordered few times from Israel on 300ml - 400ml.