Perth Boat Show was rubbish from a Rib perspective. The wine and seafood were pretty good though...
There was an interesting 7.5m kiwi rib at the Hillary's Boat Show, rigged for fishing.
There are a number of people in Freo marketing ribs from NZ, SA and Venezuela.
Don't know what your proposed use is for your rib. If it's just leisure, then sure, source whatever you want from whoever. However if you have any commercial aspirations for your rib, you would be well advised to have a clear understanding of the Survey requirements in WA. You wouldn't want to have the deck ripped open on your shiny new toy just so that they can inspect your fuel tank.
I run Caprisante out of Ocean Reef and you'd be welcome to come out one day. We mainly just do Rotto although I did try Two Rocks once.
PM me if you're interested.