You can use your own domain name for your google business apps or you can register a new one here.
New domains come pre-configured with Google Apps
It's easy and inexpensive to get a custom domain and start building your business' online presence. Your domain will be automatically configured to work with Google services including Google Sites and Gmail for custom email addresses.
One year registration costs $10 and includes these benefits at no additional cost:
Google Apps Google Apps pre-configured for your domain, including Google Sites and Gmail for custom email addresses.
Full DNS control and management
Private registration to protect your personal information
Domain locking to protect you from unauthorized domain transfers
