I'm one of those cooks who buys all her spices whole and pounds them in a mortar to make customized curry pastes.
So pastel making was probably inevitable once I took up the medium. It's not particularly time-consuming if you consider that each stick is amortized over many paintings; it's something like mixing your portrait tints before starting work on an oil painting, only the colors never dry up!
Yes, I have trouble with commercial pastel sets on a couple of counts. I have a lot of small sets or half-stick assortments that I acquired while testing out various brands. After messing around with all of those for a while, I tried to settle on a full set of one brand or perhaps a couple of brands in order to have a truly full range of colors.
However, I looked at the range of colors available in the standard sets and couldn't justify spending so much for so many I probably wouldn't use very often. Their selections don't have a lot to do with my color sense, and buying multiple sets tends to get you duplicates of boilerplate colors rather than a broader range. My budget is very finite, so I have to be careful with purchases. I can't afford to buy a big set of high-priced pastels and basically throw away a quarter to a third of the sticks. I could buy open stock, and I have plenty of random sticks that I got that way, but that adds up fast and still doesn't get me where I want to go. In my most-used areas of the spectrum, there never seem to be enough shades in commercial brands to cover what I want to do.
So it comes down to making my own; after a couple of years of head-scratching, that's what seems to work best for me. I'm a bit of a pigment wonk anyway; I've got sheets of pastel test swatches that I've exposed in south-facing windows and all that jazz.
The main problem is finding reliable pigment information for pastels specifically, rather than for watercolor or oil. Pigment working characteristics in dry sticks are a whole different ballgame than in liquid binders. Just for instance, ultramarine is notoriously stringy in oil and usually gets plenty of things added to it for manageability, but in pastel it is so perfectly velvety-textured that adding it to any mix will improve the qualities of the finished stick.
If handmade pastels were the only selling point for my commissions, I'd be selling the pastels instead.
Without getting into all of the technicalities and boring my clients to tears, I think telling them I make my colors says something about how I approach the whole thing. (Like the daughter of a NASA physicist and a systems programmer, probably.)