The Sirui 50mm T2.9 1.6x Full-Frame Anamorphic was initially launched on indiegogo but it can now be preordered at B&H Photo.
Other Sirui Lenses
Sirui 75mm f/1.8 Anamorphic 1.33X:
B&H Photo
Amazon
Sirui 50mm f/1.8 Anamorphic 1.33X:
B&H Photo
Amazon
Sirui 24mm f/2.8 Anamorphic 1.33x:
B&H Photo
Amazon