Have you tried calling every TRU in Sydney? Because they might be able to hold the toy for you. If none of them have any in stock, call TRU Head Office and ask them to source one for you.

When I was hunting for MP Optimus Prime last year, I called every TRU in Sydney on the day it came out -- the next morning I kept trying and managed to source one at TRU Castle Hill who were happy to put one aside for me. But I remember when I called TRU Head Office on that first day, they told me that I couldn't find one within a week or so to call them back so that they could source one for me. So yeah... try that way?
http://www.toysrus.com.au/www/732/10...de=2&state=NSW
http://www.toysrus.com.au/contact-us/

Wow... has MP Soundwave sold out that quickly?!? It sounds like MP Optimus Prime all over again. Although TRU did restock on MP OPs around Xmas/New Year time, and stock was plentiful enough that I saw toys on shelves for quite some time after that restock. Hopefully they'll do the same for MP Soundwave.