Is Chevy Camaro 1998 Airbag Control Unit Japanese made?

My mechanic is charging $500 for installing a refurbished Airbag Control Unit! I don't think it is right. He also said, he had a tough time finding the right one cause my car had Japanese spec (Airbag)! GMC is quoting $800 (as per him). I asked to show me proper bill. All he has given me is a computer printout of his Garage and a $5 receipt from a wash! I think he is trying to rip me off. Can anyone help me out here?