Nourison is one manufacturer. Couristan is another.

@palimpsest I have a Couristan runner and it's good, but the pattern doesn't seem to be as well defined compared to the Karastan. I'll look at Nourison too.

I’d look for a used Karastan runner on eBay or Etsy.

@chinacatpeekin Thanks, I've done that, but runners aren't easy to find. I will probably buy something handmade for the single runner from a local shop, but any stair runner will have to be machine made.