Following up on Deepak's post about Praise Factory, I wanted to put in a plug for it.  Our church uses it, and it is excellent.  If your church is cranking out thousands of dollars for moralistic felt-board garbage, you should make the switch.  If you're starting a church, you want to use Praise Factory.

Five reasons our church uses it: 

1. Rock-solid, doctrinally sound, God-exalting, gospel-centered theology.  As a pastor, this is my #1 concern.
2. Really fun.  For my kids, this is their #1 concern.
3. It's great for church plants and small churches.  You can have a "real" children's ministry curriculum that gives parents and visitors confidence, even if you don't have a ton of time, money, and people to throw at it.
4. Flexibility... there is a ton of good material in the Praise Factory curriculum that can be tailored to your church's size and needs.

5. The price.  Holy cow, people, it's free!  As in "Free-Ninety-Free"!  Not only is that really helpful for churches on a limited budget, but it also tells you that the people behind the curriculum are generous and kingdom-minded (though I think I read something about a voluntary donation to 9Marks).