How much money should an electrical contractor charge a company for contracting under his electrical license?

In California you cannot do this unless the company is placed on your license. The qualifying provisions would be such as an RME.

If you do this you become totally liable for any work done by the other company, and I believe if you get caught doing this you may loose your license.

Before doing this I would strongly advise you to contact your State Contractors License Board for further guidelines and assistance.

This other company should hire you to perform the necessary work. If you are not able to perform this work yourself then consider hiring qualified electricians to work for you as employees and perform the work.