The kalimba was immediately commercially feasible, and the profits from AMI helped keep ILAM, the depository of Hugh Tracey's recordings, alive and well. (By the way, ILAM relocated to Grahamstown, South Africa, along with AMI, and they recently celebrated their 50th anniversary.  AMI will also be celebrating their 50th anniversary in a few years.)  

But with commercial success came copycat kalimbas.  Kalimbas don't employ space age technology. They are basically very simple instruments, so many craftsmen and companies around the world began to make their own. The kalimba was in part a traditional folk instrument and could not be protected by patent. The name kalimba itself had been assigned by an African tribe. Since this was an easier word for westerners than "mbira" and connotated musical instrument with its similarity to "marimba", this nomenclature came into general use.

Still, the Hugh Tracey Kalimbas stood above the other instruments as the original and top quality instruments.

As the world began to realize that they had a responsibility to assist political change in apartheid South Africa, it became difficult to buy Hugh Tracey Kalimbas. I heard many stories in the 1980's about how the embargo made it impossible to get the Hugh Tracey kalimba anymore, but somehow, Briggs Music in Harvard Square always seemed to have a few in their display cases.  But surely in that time of world pressure on South African imports, the kalimba imitators got their chance to pull ahead of the Hugh Tracey.