Many cichlidophiles will tell you that the "cichlid bug" is easily caught and hard to extinguish. Some call it an addiction rather than a bug. Just ask someone who's experienced it. I have and I assure you it's palpable.
It's no secret that novice cichlidophiles can't just stop at one...or two....or three fish or species. In fact, the more you read about the many species available in the hobby and everyone's experiences with them, the quicker your own addiction will manifest itself. However, after a while, you start to recognize that the first cichlid you bought is probably a species that is readily available - an oscar, convict, frontosa, yellow lab, etc. These are the equivalent of Labrador retrievers, golden retrievers, poodles, chihuahuas, and German shepherds of dog breeds. Or you'll simply get bored of keeping the species that you have. I'm neither criticizing or ridiculing those cichlid species above nor the aquarists who keep them. I'm just pointing out that they're really common species, easy to acquire, and, for the most part, easy to keep.
Part of the excitement of keeping species you've never kept is the challenge, especially breeding them. Another exciting element is the chase - trying to acquire cichlids that aren't commonly available. So where do you start when trying to find those less common species?
That's a great question, and there is no simple answer. Much depends on where you live. Larger cities typically have more local fish stores, so these cities may have greater cichlid availability. Also, larger cities typically have cichlid clubs, whose members usually include some seasoned cichlidophiles. Those seasoned members are also often part of a network of hard-core cichlid keepers with an emphasis on the word network. Expert cichlid keepers comprise a pretty small community, and they usually know each other.
I'm not part of that crowd but I'll share my experiences with you. If you want a species that you're having trouble locating, either near where you live or via online cichlid sellers, start making inquiries and get involved. Join a local club, contact a club, join the ACA, or simply find a way to engage. The aforementioned experts can be a pretty tight group. Most of those that are really experienced are friendly but they're also pretty cautious, in my experience. They're not readily forthcoming with where they get all of their fish (hint: they get many of them from each other, they know the importers, or they acquire species themselves by going on collection trips to native habitats). In my experience, these folks will try to ascertain your cichlid knowledge before they decide how much information they share with you. Right or wrong, this sums up my experiences with many of these folks.
Thus, my advice is to check around and don't be afraid to ask questions. Don't take it personally if you reach out to someone via e-mail and don't get a reply. Also, don't take it personally if you do get a response and the person doesn't give you much information. It's possible he or she simply doesn't have any information to give or doesn't know much about the species you're after. On the other hand, you may reach someone who knows how to find what you're looking for but they won't tell you. It's not all that uncommon that species with limited availability are highly coveted, and those few who have them simply keep that information to themselves. Also, remember that not every species you read about is readily available in the hobby. In fact, there are numerous species that simply aren't imported/exported for a variety of reasons - politics, cost, location. Be persistent, be patient, and remember simple economics - supply vs demand. Hard to find species in the hobby are generally expensive if you find some available.
The Cichlid Room Companion
Tropical Fish Hobbyist
American Cichlid Assoc.
African Cichlid Hub