I hadn't heard that Google is charging per user. I thought it was one payment for the year. Anyway, I found their setup too confusing so gave up on it.
Regarding CPanel and Squirrel Mail etc, are you in need specifically of webmail? If not, the normal process is to set up your desktop email client (like Outlook or whatever) to download those emails so that you never would normally log in to Squirrel mail (unless you are on the go).