Oh I know something about this!
When I was in school, we made childrens fabric books for a Christmas charity thing, and we added a layer of 'crinkle' to the pages. All we used was cellophane bags. You can buy them here on eBay, listed under party supplies and packaging supplies (some have a adhesive strip, that will have to be cut off).
We put them in between two layers of fabric, and sewed the layers together, so the cellophane was inside. You've got to crinkle up the cellophane a bit before you use it.
We did test them in a washing machine, and the cellophane inside wasn't as noisy. Hand washing was best.
Disclaimer: My opinions are purely my own, and should not be taken with alcohol. If at any time I start to make sense, discontinue use immediately.