There are massive replication delays affecting a large number of end-of-year titles and this may be one of them. It’s possible that Amazon and other retailers are temporarily delaying orders as they run through their initial allotment of copies.
The good news is that Warned Archive titles are not limited editions. Everyone who wants a copy of this will be able to get one. Don’t pay inflated eBay prices, just wait for Amazon (or your retailer of choice) to begin taking orders again.
This Amazon/Warner thing is very tiresome, it'll be back on there nearer the release date. I ordered it from Wow last week, they're selling it for just below the £15 UK customs limit, but I don't know if they ship to Australia.