If your non-profit is also tax exempt by the IRS then your subscription paper is not a taxable sale provided it is published and distributed a minimum of 4 times a year but not more than 60 times a year.
You can also put attachements as you suggest.
This publication should be helpful to you: http://www.boe.ca.gov/pdf/pub18.pdf
Note those advertising insertes and column inches are allowed if you meet those two conditions and you are also a non-profit who is tax exempt.
I apologize for not getting back toyou sooner on this. Your question did not show back up in the Que.
From what you are stating, the newspaper subscriptions do not appear to attract sales tax.