Hi,
It really depends where you are going. Supratek is in Perth (West Aus), Adelaide (South Aus) has VAF research speakers and Sonique speakers, Halcro is there, and T.M.C. cables if youre really keen, but the majority of companies are on the East Coast. Sydney has an excellent shop, Len Wallis Audio (they stock Perreaux). ME amplifiers and Dan A Digital speakers are also there. Melbourne has Redgum Amplifiers, Osborn loudspeakers, Whatmough, and as you say youre interested in auditioning a sub, try Whise in Melbourne.
Dont try anything you see on The Crocodile Hunter, the man is certifiable! But I definitely second the Hogs Breath Mdomnick!