Never seen a blue ringed octopus in person, but the pictures and clips make them look amazing, the rings flashing on and off all over their body as they move. Did you know they don't produce their own venom? its the same toxin, a voltage-gated sodium channel blocker called tetrodotoxin, originally recognized in puffer fish (order Tetraodontiformes, hence the name), (in)famous for the japanese 'fugu' sushi, that knocks off a few diners a year from either eating too much, or eating it when it has been prepared with insufficient caution (the TTX within puffer fish is not evenly distributed, primarily within the skin, liver and innards, less in the flesh, but its still there)
Also found in some Amphibians (fire-bellied newts, genus Taricha, people have died from swallowing one of these little critters in the US as a stupid dare. Serves them right if you ask me. Also found in certain toads, of the genus Atelopus)
Hey, since you are local to the right area, could make a little cash (come to an agreement if your up for catching the little devils) I've been very interested in getting a new pet, and of the three candidates, a mouse spider (genus Missulena, not the araneomorph by the same name.) is high on the list, but I've never seen them for the 'unusual' pet trade, the other two ideas either being a Parabuthus scorpion, or more widows. Successfully bred brown widows (Latrodectus geometricus, native to the US, was rather surprised to find one in my kitchen one night. And it wasn't a mis-ID either, because the little bitch bit me once and I got what for. They usually aren't pissy, but this one had just laid egg sacks, one of which hatched, the other...ugh, I hardly like to think about what happened to them, all of them. Fucking butchered by the pigs after an illegal raid on the place. MICROWAVED for fucks sake.)
And I've been pet-less ever since. More ideal keeping animals here that can't wander. At least, not outside of known areas, so another cat isn't really practical, not a dog person, and either of them could knock over something either valuable, or full of something that would harm or kill them, or lose me a lot of money, so another invertebrate pet is ideal.
Which area of aus. are you from? if you don't want to give a personal location, I don't even mean city, just general territory or compass direction, to get an idea of whats out there. I have something specific in mind, ever see M.occatoria round your area? large mygalomorph, quite distinctive, legs similar to Atrax or Hadronyche, and not dissimilar in build, indeed M.bradleyi, could be easily enough taken for a stockily built funnelweb. And rather oddly, the venom in the family, or the active primary component to it, missulenatoxin acts similarly to robustoxin/atraxotoxin from the funnelwebs and Hadronyche, its SO similar, despite them not being in the same family, that Atrax/Hadronyche antivenin is crossreactive with mouse spider venom. The males are the ones liable to be seen, as they are active hunters. Real good looking critters, bright red chelicera and just behind, and a metallic cobalt blue abdomen. The females are unlikely to be found unless actively searched for, as they spend most of their life in a burrow, like a trapdoor spider.
NOT one to get bitten by, if you are willing to keep an eye out while your out, as I mentioned, venom is pretty similar to funnelweb venom, although they are less likely to bite, and if they do, much more prone to giving a 'warning' dry-bite. Any export permits, I'd pay for of course.
Other potential pets...all seem to be arachnids for some reason, most of the land-bound families are interesting, although some are either impractical to keep, like the Solifugae (aka 'camel spiders' although they aren't spiders, impressive looking, but apparently incredibly hard to keep alive in captivity, possibly due to an insanely high metabolic rate, not surprising given the speed of the things, and that, lacking venom, they depend on a combination of speed and the 8-legged equivalent of a face made out of bolt-cutters. Not dangerous to people, but all the same, I'd not want to try keeping one, if expert arachid-keepers can't keep them alive for more than months.)
And (tail-less) whipscorpions are kind of appealing too, quite harmless, aside from being able to give a nip with fairly large chelicera, or swiping with their spiked, mantis-like claws. Aside from the vinegaroons/tailed whipscorpions, scorpions, and those whaddyacallem.....spider-shaped creatures...nonvenomous, mygalomorph spider type build, and very, very primitive, still bearing the abdominal segmentation as a vestige of evolutionary divergence of spiders and scorpions, the rest of the family, excluding harvestmen, you'd never see them kept as a pet, or else if you do, you don't want to (ticks...ew. I'm an animal lover alright, but ticks? even a tick's own mother couldn't love one)