Delicious colors, eh? Once, when I was flush, I bought this set of colors at a pastel workshop. Unison. I haven't used them that much. I love to look at them though.
I also bought some expensive sandpapery pastel paper. It's supposed to help with layering the colors. I didn't do much layering here. I think you're supposed to use harder pastels for the initial layers, softer for the later top layers.