The cichlid Altolamprologus compressiceps "shell" or you may find it under Altolamprologus sumbu is around in the hobby. Its not something that is commercially bred, and so it is usually found among hobbyists. You can leave a message in many of the trading posts areas that are on most cichlid forums and that lets people know you are looking for it. Hopefully you can get some leads that way. Also try www.aquabid.com
, but just make sure you check references well before you send your money away.
Also you can try the Wet Spot in Portland Oregon, they have a wide variety of cichlids, and if they don't have it, they maybe able to locate it for you. It would be a fun road trip! http://www.wetspottropicalfish.com/
Also check out hobbyists breeders in your area: http://www.gsas.org/
Just get the word out that your looking and you should be able to find them.