A year or so back you were able to pick up a 28 head in OZ for around $50 to $100, and they were cheaper in the States.
Now if your lucky to come across one in OZ they are over the top, and the US prices are on the climb.
I managed to pick up a couple a while back when they were cheap, so that's one less thing I have to worry about in years to come.
Here is one on offer on US Ebay, with a bid of $200.
On the other side of ridiculous is another one in the States, with an asking price of $895, and hopefully no one is that desperate.