It's funny because a couple generations ago the .38 Special was far and away the king of the range. It's nowhere near what it once was, but it was so prevalent at one time that there are still lots of them around. I think of this whenever I hear someone say that the .40 S&W is dying out and someday will be dead to where they won't make ammo for it. Not likely; it was just too prevalent, and will always be around to one degree or another.Even in good times, commercial .38s were more expensive than 9s -- probably a volume-to-price (*) issue. Almost everyone has a 9mm, but fewer have .38s and it's easier to blow through a lot of 9mm compared to .38s so the volume for 9mms has always been greater than for .38s.
* economy of scale, that's the term I'm trying to find
I wouldn't have the slightest concern about primer availability if I hadn't got on a big .38 reloading kick a few months ago, and used up 5k SPPs. I had too much spare time at home "working from home" at the beginning of COVID, and decided it was a good time to tackle that 5 gallon bucket of .38 brass sitting in my garage. At least I have a five year supply of .38 Special ammo though.