Oh and this is a picture of White Calvus.
http://www.irmascichlids.250x.com/A.calvuswhite.jpg

This is a picture of the commonly available black Altolamprologus calvus:
http://www.kingcoral.com/calvus.jpg

I have 12 young black calvus here in Sydney. An adult breeding pair of calvus is worth about $600 here in Sydney... They take about 2-3years to mature and grow painfully slowly.

I think black calvus in Malaysia are worth something like RM60 for a 1inch fish... so they're not cheap either.