I used music that's already out there for a couple of reasons. First, it wasn't getting published, so I didn't have to worry about copyright or persmission. Second, the kids wanted something easy to sing - so use a song over! They love it! Or, use the melody and change the words to fit your theme. Third, there's plenty published that they haven't sung yet. I tried to mix some familiar ones with just a couple that were new to them.
Since I wasn't publishing it, I recycled a lot! Or, I'd start our recyclying, then rewrite and find out that it was really different. Either way, I used lots of resources.
My church and I have several books on games, snacks, crafts, etc. I used those to either copy the idea or launch my creativity. Oriental Trading has cheap kits that do the trick, too (crafts.)
If you don't have those kinds of books readily accessible, ask to borrow old Sunday school and VBS material. There's usually a wealth of untapped ideas in those. Also, go to other churches and ask if you can use their library or teacher materials for a day. As long as you stay on the premises and offer to pay them for use of their copier, I think you could turn up quite a bit.
Remember that not all your games and snacks have to follow the theme. Do some just for fun or just for refreshments. And, your snacks can be the craft project as well. Edible art.
