I started doing the large hallway bulletin board at my kids' school (a small, private Christian school) this year, and I've been using the Cricut. I would recommend A Child's Year - it has some beautiful silhouette cuts on it that are simple & striking, including several reading themed ones.
I also agree with the Everyday Paper Dolls, Paper Doll Dress Up, Animal Kingdom, Create a Critter & Create a Critter 2, and My Community (surprisingly, this one has some fairy tale themed cuts).
Some other suggestions would be My World, Winter Frolic, Walk in My Garden, Once Upon a Princess, and Dinosaur Tracks.
In addition to eBay, you might want to check out
Etsy - Your place to buy and sell all things handmade, vintage, and supplies. Some sellers have carts at really reasonable prices there.
HTH!
Marcy