What should it cost to have brake rotors replaces for each wheel?

My 2008 Honda Element has begun grinding when I apply my brakes.

Added (1). What should it cost to have brake rotors replaced for each wheel?

Repairpal.com.
They can give a good center-line on parts & labor costs.

I do my own brakes, I can do mine for about $65 per rotor. A brake shop may charge up to about $180 for each rotor.