Make their own.
I got a sample box from
Terry Ludwig who began making his own sticks out of frustration and joy of the craft. I mentioned how hard it is to find nice darks and he mixed me up such a wonderful set!! He even included a medium for whitening the ones I like by grinding them up and adding the white glop for a lighter value stick.
I am trying very hard to incorporate soft pastels into my work, but I feel very timid. I am a hard nupastel and Holbein fan. I think the very reason is that by using less I can blend more. The limited palettes of the two sets I use, make me create by blending. When I used softer sticks, it was more of that picking just the right one among hundreds to fill up the paper texture and leave it. Soft pastels are not subtle to my way of thinking!