I believe Midway has some of this stuff. I know I saw it in one of the big outfits Midway, Cabelas. I was surprised as that round has been oboselete for ages. It was either Winchester or Remington that did the run.
The reason I ask is that the .32 Colt Long centerfire external dimensions are the same as the 32 Long Rimfire. Some rifles had a firing pin that could be flipped for centerfire or rimfire, or came with two firing pins. And gunsmiths have converted rimfires to centerfires.
Old Western Scrounger used to have .32 Long Rimfire as recently as 2009, new, but it wasn't cheap. Like $49 a box of 50. Alas, they no longer list it.
I've got as couple of hundred rounds of this stuff lying around for a couple of rifles, one being an Steven's "Favorite". I also have some .41 short rimfire for a derringer I own.
They make runs of this obsolete ammo every few years once the supply of the previous run has dwindled.Be patient as this ammo is available, but you have to search for it a bit and will be salty once found.