How much does it usually cost to replace the box outside the house where you turn the electric on and off?

The electrician told me that i need to replace this box outside the house. i dont remember what its called now. How much does it usually cost to replace it? He sait its too small and missing the copper tod which is supposed to go to ground from the box. He gave me an estimate, which sounded way too much. i think you are right. Its the main panel. I know its not the meter.