The Chinese C melody was only started because Steve Wedgwood (Aquilasax) commissioned several hundreds from a Chinese factory not because they spontaneously went into this market, after the exclusivity agreement expired they started offering them on the open market since Aquilasax had created the interest and they still had the tooling.
The metal clarinet is of no real interest to the Chinese makers ( in Taiwan there are no clarinet makers).
Because it is more expensive to make than a wooden or plastic one and because the clarinet market, small as it is and loaded with secondhand clarinets , doesn’t really see these favorably.
The majority of these metal clarinets, often misidentified to be soprano saxophones, are not rare or sought after. There are, of course the exceptions and some have quite a following among specialized collectors.
In Turkey there is quite a tradition for metal clarinets with Albert system and tuned in G
Generally poorly made and with terrible intonation,. this one in the picture is sold as a decorative item!
In the past the clarinets were the woodwinds which expressed the largest variety in tuning with some examples of double barreled clarinets tuned in two scales! THESE are rare and expensive oddities!
