Contstant click dependant on revs.

It sounds like there's a fan spinning and its hitting something with every revolution. The more I rev, the faster the clicking sound. Its getting louder and louder. I left the car on, opened the bonnet and checked out where it was coming from. this aint a pic of my engine but its sometihng close to it.
I've highlighted where the noise is coming from.
I recently had oil changes and timing belts changed bout 10ks ago.
The noise comes from an area underneath the hit I've highlited. Under the silvery things. Any idea on what it is, how much to pay to get fixed? And please speak in basic terms for me.
Thanks!

http://i15.tinypic.com/4zliftk.jpg

Also, its just a standard Australian magna. v6 3.0 litre.