I personally suggest Adorama, Amazon, Ritz, B&H, Calumet and J&R. I can't vouch for ads below.

Zeiss 18mm f/3.5

Zeiss 21mm f/2.8

Zeiss 50mm f/1.4

Zeiss Ikon

compared to Leica and Minolta

Zeiss ZM 18mm f/4

compared to Leica 18mm f/3.8

Zeiss ZM 28mm f/2.8

Zeiss Contax G 16mm f/8

Zeiss Contax G 21mm f/2.8

Zeiss Contax G 28mm f/2.8

Zeiss Contax G 35mm f/2

Zeiss Contax G 45mm f/2

Zeiss Contax G 90mm f/2.8

Zeiss Contax G 35-70mm f/3.5-5.6

Zeiss Contax 645 35mm f/3.5

95mm filters.

review coming.

get them here

Zeiss Contax 645 45mm f/2.8

72mm filters.

review coming.

get them here.

Zeiss Contax 645 45~90mm

review coming — when someone loans me one.

get them here.

Zeiss Contax 645 55mm f/3.5

72mm filters.

A lighter, less expensive lens for the Contax 645.

review coming — when someone loans me one.

get them here.

Zeiss Contax 645 80mm f/2

72mm filters.

For use at f/2, I suggest the Contax 220 vacuum back (or a digital back); the standard back doesn't hold the film consistently flat enough for great results at f/2.

review coming.

get them here.

Zeiss Contax 645 120mm f/4 Makro

72mm filters.

review coming — when someone loans me one.

get them here.

Zeiss Contax 645 140mm f/2.8

72mm filters.

review coming.

get them here.

Zeiss Contax 645 210mm f/4

72mm filters.

review coming — when someone loans me one.

get them here.

Zeiss Contax 645 350mm f/4

95mm filters.

review coming — when someone loans me one.

get them here.