For my old Ion, I paid a mere $25 for the tiny light weight, 2 LED torch. It had a simple elastic band with a tightening toggle, which never needs adjusting for your head size after the first time (the elastic is enough to hold such a tiny device in place).
Unfortunately, when packing for my last walk, I found that my head torch was missing, so I had to borrow my wife's (fancier with more functions - and more expensive). I think I must have left mine in Ironstone Hut on my previous walk.
In any case, today I finally replaced my old head torch.
However, this time around I found something even better than my old Ion: The new Black Diamond "Ion". Yes, that's right. The new model cost $35, but for my needs it is still the best value for money. The new model has only 1 LED (so presumably uses less power), but has a much more tightly focused beam (very tightly focused, which may not suit some people). The new model also has a high and low function (hold the button down for a bit to turn on/off, and press quickly to toggle between high and low).
Oh, and the battery is included (a single standard 6v battery - the one that looks like half a AAA battery).
Here's a couple of images showing the old and new Ions...
Old Ion:
New Ion:
Sure beats my first head torch, which was a large incandescent Petzl with a huge battery back on the back of the head.
What do other people use, and why?
). I'll have to look out for it in the supermarket next time I go shopping. I couldn't find any pictures of it after searching for a bit. 
