On a now kaput forum, I used to exchange notes on African tetras with a woman in the southern US somewhere, years back. She and you are the only keepers of Congo tetras, beyond interruptus and caudalis that I've ever encountered online.
I could post a lot if anyone here wanted to discuss the ins and outs of killie and lampeye keeping, but it's the same problem. There aren't enough keepers around. One importer brings in 30 fish once every year or two, and we buy them from that lot. What happens to the others in the lot? Some sell to people who don't discuss. Some never sell and die at the importers'. Some go to public aquariums.
We discover we're the only people with the fish, soon enough. It isn't a snob thing - it's something I find frustrating. If I could get the African tetras I used to have again, with the aquarium set up I have now, breeding would be my priority. But now, I can't afford to buy a group of six to ten $30 tetras. I used to make much more money from the fish than I spent and I could put fish money aside and play in rich guy world, but no more.
Alas, I'm afraid we're doomed. You're stuck with me. Reheboth in Florida may start with more Congo fish. Below Water in Canada will occasionally, though your border restrictions make them hard to get fish from. The Europeans will get them regularly. But among English language aquarists, not many people explore the exotic species. Culturally, we have an increasingly dull, conservative approach to fishkeeping.