This is a regular ask on this forum, but as probably the only puppet-person here, I'll come up with a decent answer so that other people know where to look too.

1. Find out who else has produced the show in your area, and see if they have any Audrey puppets they can hire out, lend, or if they have a contact that does have them.

2. All else fails, contact UNIMA, the Australian organisation of puppeteers, who can point you in the right direction of a hirer, builder, or designer. www.unima.org.au. You may also want to check http://puppetryaustralia.info, and http://puppetrynews.com (the latter is a Sydney-based puppet builder/performer, and may have some contacts). And though it's US-based, there's a lot of Aussie puppeteers on the following forums: http://puppetsandstuff.com. This thread follows on one of the US puppet makers creating an Audrey II:
http://puppetsandstuff.com/community/index.php/topic,2807.0.html

3. Check these threads. Some may be old, but they might provide some contacts.

http://www.theatre.asn.au/node/9746

http://www.theatre.asn.au/node/7160 (Wow, I'd forgotten I'd posted this one)

4. Contact The Puppet Shop in Sydney, and see if they have anything: http://www.thepuppetshop.com/

5. Ask around on these forums, someone might have a contact or some puppets to spare (which, of course, you've just done)

Puppets in Melbourne

Sticky Apple Legs

If anyone is interested I wrote a blog post on this topic that has more info:

http://puppetsinmelbourne.com.au/index.php/faq/2008/02/17/where_to_find_audrey_puppets_in_australi

Mini-monster puppets customised just for you! at
Puppets in Melbourne