You could try e-mailing DHW directly to see if they have any old stock. Price will be staggering. If memory serves, this lens is without helicoid focusing mount and requires either the zoom extension tube 22-68mm or the bellows to focus, which will also be hard to find. Two alternatives for you to consider: the older non-PQ Zeiss S-Planar 120 (the later PQ/S versions are prone to flare in my experience); or the 150/4 Schneider PQ, extension tubes added as needed.