The time I loved my AIS reciever was out in Bass Strait and also south of Eden at 1am, and so for me, and this is my opinion only, I would recommend a proper receiver if you venture far. Once you start getting that feeling of security from Open CPN showing possible collision tracks, you become a believer and any money spent is a non issue.
I bought the Daisy. It cost me about $60 but is more now. Coupled to Open CPN (which is free but the charts are about $70) I have a nice system for under $200 (not including the laptop - but I have a spare laptop which is too slow for work but fine for the boat)
www.tindie.com/products/astuder/daisy-2-dual-channel-ais-receiver-with-nmea-0183/Good and cheap for offshore. My friend uses the app and gets quite good coverage along the coast. It is a good thing to have coast sailing along NSW but would be a bit sketchy in Queensland where mobiles aren't so well covered.