I searched completed auctions on e Bay and only found one. The one you highlighted is up to £360 as I type this, or about AUS3, so I suspect it might go a little bit higher yet.
(Eminescu; trial of a translation: " 'Cause life is a lost good, if man did not live, the way he would have liked it.")Lord Nibbo, The price of the 444 is high simply because it is quite a rare plane.
There is another one for auction via e Bay in the States at the moment that is up to US$733, or about AUS$877, with about 2-1/2 days to go.
It is interesting to note that the sellers of both of the 444's being auctioned at the moment will only post the item to buyers in their home country.
I would have thought that the sellers could potentially get a higher price if they opened the auctions up to buyers worldwide.
It was only made between 19 according to B&G so it's down to simple rarity.
It's be interesting to have one from a purely user's perspective, and see whether it's really as unusable as claimed.