I COULD fall down the rabbit hole of buying all the micas... but I stopped myself by deciding, and following through on it, to get a set of "average" or "mid-point" colors for the 6 big rainbow categories: red, orange, yellow, (edit to add because somehow I missed it) green, blue, and purple. I have a couple other colors, notably white, black, a special green, and a couple neons. As well as a grey/silver and a gold. But by and large for the time being I want to stick with my "average" colors and carefully try to blend what I have to accomplish different colors. That way I'm not buying (and having to store) all the different hues I may want to experiment with. And as a hobbyist, this will challenge me in different ways. How can I accomplish the effect I want with what I have? Learning to think about color theory, blending, saturation, etc.
Now if I ever start SELLING soap, for consistency & time savings I'll buy more colors. I might even pick up some one offs here and there. Like if I ever want to do a pink bubblegum color...