The usual CT-Asia from Ukraine...
or one of the Japanese keys I recently found in Tokyo.
On the left, the older Dentsu-seiki
telegraph key (same company before they started to use the Hi-Mound brand).
On the right, the newer HK-703 Hi-Mound Key.
Dentsu-seiki
key was purchased in the Tokyo Fleamarket at Oi Racecourse. The seller was
asking 3000 yen (about US$20) but I could not resist my instinct to
negotiate. We made the deal at 1500 yen (about US$10). I don't know the model number - it is a simple, inexpensive key but of good quality and feel.
Later I visited the Tokyo Radio Department Store building in Akihabara and found a newer HK-703 Hi-Mound Key in excellent condition offered at a price of 4500 yen (about US$30) as
well as some very useful small electronic parts, connectors, knobs, and
hardware from the vendor booths.