Wow, good tutorial. I have to be honest, when you recommended a cookie cutter at the start, I was skeptical about how it'll turn out, because I thought that you'll just leave it as a simple flower shape. But after reading the tutorial, the little details you added with the pin and knife really makes the flower look fantastic. Good job!
I found it in a set at my local Hobby Lobby craft store. I've also seen them in Michael's craft stores, but the last time I walked into ours they didn't have them anymore. It might just be that one store, though.