When I was visiting The Grove Community Church in Riverside, California, I saw a kids church reward system that they used to help motivate kids to listen & participate. They also used this system to encourage families to work on the family activity page together, and to return it the following week.
They used ping pong balls to give to the kids when they brought their Bible, or a friend, etc. At the end of the service, the kids could put the ping pong balls that they earned into their display box. The group who filled their box first was rewarded with a pizza party. The display boxes were located in the hallway, so that kids and parents could both see the progress that they were making.
The boxes were made with wood, and a plexiglass face. There was an opening at the top for kids to put their ping pong balls in at the end of the service. They were narrow so they did not take up a lot of room in the hallway.
I liked that the kids church reward system was visual for the kids, and they worked together to achieve a goal. Churches with a limited budget often find it challenging to find prizes that kids will want to have, but do not cost a lot. This idea allows kids to get an immediate reward (ping pong ball) and still be motivated from week to week to try to earn the pizza party for their team. Often smaller prizes are not good quality and end up being thrown away soon after the kids lose interest in playing with them. This system allows for teams to work together to achieve a common goal. It is ongoing, and takes several weeks to get to the goal, but if everyone does their part, they can get to the goal faster.