I bought my last 2 cars from interestate (i used to be from another state)
just get an RAC equivilant company to inspect the car and email you the report or if u want an extensive report like C-reds with compression test etc
then you'd have to call up a few well respected workshops to carry out an examation
you have to take it over pits to rego it in WA but if its stock its no dramas just $56.50 pit fee + rego (approx $500 for a year) and stamp duty (2.5% of cars value i believe?)
i used autotrans to transport my cars as they have insurance that covers the car while being transported so you dont have to buy insurance until it lands (i heard TNT is quite well too)
ask all the usual questions like reason for sale, when was the car imported, service history, any accident history, current faults mechanical/cosmetic etc etc
ps. dont fly over and check it yourself coz if its a lemon its outta your own pocket (did it once and never again)