Lot 65 estimated $ 120K is an example from the early 1930s. It was sold for $ 210K including premium by Bonhams on September 21, 2015, lot 73, accompanied by a video. I narrated the early history of the Enigmas and this specific machine as follows before the Bonhams sale :
The wireless telegraphy using Morse code is an elegant solution to transmit information, especially in war time, but its security is questionable. In 1926 the Germans discovered with dismay that at the end of the war the British intercepted and read easily their most secret messages.
The solution existed in their own country. In 1918 an engineer working in Berlin invented an enciphering machine in a high level of complexity. By its process of changing throughout the connected network the settings applicable both in transmission and in reception, messages must be inviolable.
The extreme subtlety of Enigma lies in the fact that the coding of a letter changes continuously by the action of the rotors according to an algorithm that applies to all machines. The basic plugboard wiring and the initial position of the rotors are renewed very frequently, even daily on the most secret networks, by instructions transmitted to the operators.
When hitting a key, the electrical signal is transmitted through the three rotors to another component named the reflector and passes back through the rotors to light a small bulb which reveals the reading value of the letter. The German military developed additional complications such as the interchangeable rotors or the movable reflector.
The machine for sale is of the first type with three rotors. Its elements have been kept in matching numbers, which is very rare. The serial number indicates that this Enigma dates from the early 1930s, in the transition period between Reichswehr and Wehrmacht.
Lot 66 is a three rotor K model made for Swiss use ca 1939. K means Kommerz. It was sold for € 31K before fees by Breker on November 7, 2015 and is now estimated $ 70K. Another three rotor machine from the same period was sold for £ 133K including premium by Christie's on September 29, 2011.
The M4 variant adds a fourth rotor along with further complication for use by the Kriegsmarine to transmit their most secret messages. Most of the M4 were destroyed in the sinking of their submarines in the Atlantic war. Lot 67 estimated $ 350K is an M4 made in 1944. Another M4 was sold for $ 365K including premium by Bonhams on October 21, 2015.
RESULTS INCLUDING PREMIUM :
early 1930 s : $ 81K
'Swiss' model ca 1939 : $ 75K
1944 M4 model for Kriegsmarine: $ 435K