Commercial skipper and SAR Mission Coordinator currently completing my CPL. The big PLB sellers in Australia are the GME (
https://www.whitworths.com.au/gme-mt410 ... b-with-gps) and the RescueMe made by ACR: (
https://www.whitworths.com.au/ocean-sig ... beacon-plb)
Either way, make sure you get one that has GPS as then the accuracy will locate down to within 100m.
I'm a big fan of Garmin product, and their answer to Spot is InReach. It's important to know that neither is exactly a PLB in the textbook sense. A PLB is just like an EPIRB, but instead of being registered to a vessel or a machine, it's registered with the Australian Maritime Safety Authority to you personally. AMSA are the main agency at the Joint Rescue Coordination Centre regardless of whether a SAR activation involves a boat/ship, aircraft, or someone lost on land. When an EPIRB or PLB pings in Australia's area of SAR responsibility, you'll have every available air, land, and sea asset on the case quick smart. A PLB will transmit at 5W for over 24 hours on 406MHz to the COSPAS SARSAT satellite system, and provide a 121.5MHz homing beacon for rescue services.
Spot and Garmin InReach are private subscription-based services so there's a middle-man between you and the JRCC. Spot is used by a lot of people working in remote areas as it leaves a bread-crumb trail of your movements. Handy if you're not able to activate your PLB, but really they achieve two different things.