Deb's decals is a good place to buy such things.
Most of the posts I have seen on them rate them high on quality and workmanship. I personally have never used one.
Not to come down hard on you, but did you read her listing on eBay?
"If anyone wants to contact me directly, my email address is: debsdecals@gmail.com"
I was replying to your question about what they are made out of.
My apologies are tendered for your consideration.