From Leopard Gecko Wiki
The Black Pearl morph is currently in its developement stages. The European breeder, Living Art Geckos and Asko Kampinga have been working on the project. According to their site, the Black Pearls first appeared at a Dutch zoo which had received a shipment of Leopard Geckos from the wild. In 2006, Living Art Geckos and Asko Kaminga received some Black Pearls. As of right now, they and the Black Velvets are the closest geckos the Leopard Gecko Community has to Melanistic Leopard Geckos.
The Urban Gecko released a set of Black pearl geckos which they had bred from what they recieved from the European beeder. The Black pearls sold for 3000 dollars each on their website.