I'm struggling with that. My red, orange, blue oil pastels are running out. But have a bunch of brown, grey hues left. So forcing me to adapt. Also, was struggling to figure out how to add layering, depth, large areas of white space. But just one tiny white oil pastel. That forced me to experiment with using gesso as a medium. Initially, just to more cheaply add more white space. But realized gesso is amazing, can be sculpted, if you sculpt patterns, or carve lines into gesso, let it dry... when you lightly run oil pastel over the dried gesso...

Poverty, limited means can be useful. Necessity breeds adaptation.