G'day Muzn.
Iam near Perth also, my experience is that people are reluctant to share/advertise their spots.
Bit like getting information from a fisherman.
At the risk of being proven wrong by someone who knows a lot more than me. I think that our WA is Geologically one of the oldest areas on earth, thus weathering and erosion has taken it's toll on our minerals making good fields rather scarce.
The Pilbara, Hamersley, Nullagine, Marble Bar areas have some good rock, but hardley on our door step!
A good place to start is by joining a club, the
WA Lapidary & Rock Hunting Club, are very reputable and run field visits both locally and further a field from which as a member you can benifit from and learn.