Salary question- going rate for student editor

Hi all-

I am a second-year college student in the US and just finished an unpaid summer internship. My primary job was editing a book manuscript for grammar, clarity, style, fluidity, etc., before it was sent on to the publisher. My boss has offered to hire me to do the same kind of editing on his next manuscript, and has asked me to find out what the usual pay would be for a student doing this kind of editing.

So- have any of you done this kind of work? What’s the usual pay? Is the rate by the hour? The page? The word? What’s the salary for professionals, for those just starting out in the business, and most importantly, for students?

Thanks for your help-- I need answers on this ASAP.

-Zahava