[Drum Master 1]

I'm sure they have tried other metals, one that comes to mind is Nickel which is a 20th century discovery. Some manufacturers use Nickel to harden or stiffen the alloy, but it makes them very sharp sounding, too clashy.

Most Turkish cymbal makers use Tin for this purpose, as did the Sufi.

As for Gold... at $1,000 an ounze I don't think many people would be throwing Gold into the mix on a whim, just to experiment...
Unless of course they had heard the rumours about the Sufi using Gold, which was a very closely guarded secret, held by a select few cymbal makers... who took the secret to the grave with them.