Getting new Celestron bits from the US can be a pain. Celestron's contracts with their retailers does not let them sell outside North America. Shop around the Oz distributors and you might find better prices.
Bintel sell solar filters but I'm not sure they have one to fit your scope. You could ask.
MyAstroShop sell Baader and Thousand Oaks. Look on the
Thousand Oaks site for their list of sizes. I'm about to send an order for a couple of TO glass filters.
Telegizmos do good scope covers.