Skydive Express is certainly one of the more modern outfits in terms of aircraft and facilities. Nice and close to the town of York too if you want to get away from the DZ for a coffee and a meal or just head to the pub.
WA Skydive Academy operates two C182s. Used to have a PA31 until they kept running it out of fuel.
Hillman Farm is the only truly club operation in WA. It's a bit of a drive but the atmosphere there is great. They have a C182 and occasionally use Busselton's Islander.
Busselton doesn't do too much these days but maybe worth giving them a call also. Friendly bunch of ex military types.