Assigning current color to a variable for fade out (C#)

I'm having trouble figuring out how to assign a game object's current color to a variable. I plan on altering it to make items of different materials fade out. Some of the variables I've tried are these:

 public Color thisColor = renderer.material.color;

 public Color thisColor = new Color (gameObject.renderer.material.Vector4);

but I get an error that an object reference is needed. I've tried it every way I could think of, but I don't understand what I'm doing wrong.

I also tried copying the example here: http://docs.unity3d.com/Documentation/ScriptReference/Color.Index_operator.html and while it stopped the editor from complaining, I couldn't make it do anything.