This year for my daughter's school class Halloween party, I just made the personalized cards above via Zazzle in the business card size. You can use the same template and change any of the words.
They cost $16.95 for 100 so you have plenty left over for next year or if you have more than one kid, you will have enough. If you are planning a party, it's a great addition to the party favors.
It could also serve as a Save the Date type reminder by gluing a little magnet on the back to include in invitations.
I already have a small Stampin Up puncher and brads to use to fasten the cards to the bags. You can use a regular paper puncher for the same effect and ribbon, yard or string. This is a great project for your children to do to encourage creativity.
Before you purchase anything from Zazzle, always check to see if there are any coupons or special deals.