The new ArtraLab Nonikkor Nocty 50mm f/1.2 is now available for sale at B&H Photo for $398 (see all ArtraLab lenses for Nikon Z-mount).
ArtraLab lenses are also sold at Amazon and on the official online store.
Previous coverage of ArtraLab lenses can be found here:
The new ArtraLab Nonikkor 24mm f/1.7 APS-C lens for Nikon Z-mount is now available for pre-order