After *05 Oct 2016*: , I figured out a new Trick to change the Primary Domain for Google Apps.
Also i can added 2 more Secondary domains with 5$ per Secondary domain.
I will help you change your primary domain or add secondary domain for your Google Apps (GApps) Free Standard account. Each account are only allowed maximum of 2 secondary domains
www. fiverr. com/hostvn/change-primary-domain-google-free-legacy