Not impossible to find; Oliver @ Below Water had them on his list for sale this month. I also have seen them on European lists lately.
I've three, bought from Rehoboth Aquatics last time Toyin got them in about 3-4 years ago. They are an extremely shy species and dislike coming out in light, and they aren't nearly as aggressive or opportunistic about feeding as many other synodontis like S. euptera, S. ocellifer, and S. notatus. As a consequence of this, mine are pretty difficult to feed as they are out-competed by other synodontids in my tank.
"What did the Caspian Sea?" - Saki