Why not do quarter or half page invitations in a script font that says something like:
You are cordially invited to take an active role in your child's school experience. The _______ Elementary PTO/PTA will hold it's first meeting of the year on ______ (date) at ________ (time) ____________ (location). Your presence will be greatly appreciated by the membership and by YOUR CHILD. No RSVP required, your presence is our present!
Do you have any cutsie reminders we can send home. I'm getting tired of the same old form. I'm thinking of some cute invitation type thing, but of course cost is a factor - we have 475 kids.