Daniel,
I can't think of anyone off the top of my head that stocks Hamman in OZ but I have seen Hamman stuff advertised fairly heavily in the British mags 'Total BMW' and 'BMW Car'. No doubt you'd know these mags. Checkout the Euro parts website (soory no link). They or a like firm may be able to ship the genuine articles to you at a reasonable cost. Keep an eye on the exchange rates and order at the best time. Another option is to contact your local BMW Club. There's always a wealth of information in the club movement.
Cheers
Wingman
'89 525i/A Exec 193000kms
'94 Subaru Liberty AWD Wagon
Looking for Merc 300TE
NSW, Australia