Good news, everyone!  (I sure hope it is, anyway).

I rang AP on Friday and they told me basically what I already knew and that I couldn't lodge an investigation unless it hadn't been delivered by close of business today. Lo and behold, I woke up this morning and the tracking has finally been updated (processed through a facility in the buyer's city), so I just hope it gets delivered in the next day or so. 

But, from the Tuesday after Australia day to now, that's 3 weeks and counting - nearly two weeks between being sent from Oz to showing up in the US. >_>