Hey Big Kev
Us West Aussie have to be dedicated to get a decent collection going.
There are a couple of east coast stores that will send to WA with all of the right paper work in place and I hope there will be more in the future as the 20 plant ruling is taken up by more sellers.
Here are two that I know of witch will send to WA with the required paper work
There is also the cactus & succulent society of Western Australia which is always a great source of info and plants. I can get the date of there next meeting for you if you would like.
Other than that you can run the gauntlet which I believe can be done with out to much trouble especially with seeds.
In some ways it is easier to bring seeds in from OS as long as you are not bringing anything illegal or any thing that is classified as a weed .
I have been slowly building my collection for the last four years and most of my plants have come from out side of WA and a lot of my seed has come from OS.
There are other sellers that will send to WA on the quite but I wont post there names here but if you would like to know who they are send me a PM.