100% legal in WA, 100% Illegal everywhere else in Australia, but i did some research into it when i lost my lisence (as you do) and there was a guy in Queensland selling them aswell for some reason.
Anyway its not worth it, highway patrol currently have radar detector detectors, also if they use the laser and you have a laser blocker, well its a bit obvious why they can't lock onto your car aswell lol.
But there are a few very expensive (a year and a half ago anyway) that couldn't be detected by NSW current radar detector detectors, not sure if cops have upgraded but thats something to look into aswell, but if your doing more than 30km/hr over the speed limmit there is no way you will be able to slow down in time once your radar detector activates, although you might have time to slow down to a smaller offence