There are alot of cichlids from Africa that just are not imported for various reasons. Not sure that answers your question.
Albino Cyrichromis leptosoma "kitumba" is pretty rare.
Albino tropheus are even more rare.
Both will run close to 100 each for adults.
Blue Zaire frontosa run more than that, but not rare.
Hard to say what is sought after in your question.
I'm sure Electric Yellow labidochromis are still near to the top of requests and sales due to bright color, but that does not make them rare, even though they are sought after.
Most cichlids that are "rare" are one's that people don't even know about, so therefore, they are not sought after.
i guess i can only answer your question half ways.
I gave examples of 2 rare in the hobby african cichlids that are somewhat pricey.
I gave examples of 2 popular thus sought after cichlids, one pricey the other cheap.