There are lots of websites that sell them, I know a shop in Adelaide that has them & will post. They are expensive though. I myself would just make something.

My sister made me one by painting some timber white, she attached some wire so it hangs kind of like a picutre frame & used a hot glue gun to stick on novelty pegs. I've also bought more novelty pegs & hung some picture frame wire on my wall in the toy room so I can hang artwork.