How is Taq polymerase produced?
For recombinant Taq polymerase, industrial-scale production produces liters of highly concentrated enzyme in a single run.  It comes in such small, dilute quantities when sold that only a few preps a year would be necessary to satisfy research lab demand.

I don't know the Thermus aquaticus protocol, but considering the achievements in yield for E. coli, and the minimal price difference between the two enzymes, I'd imagine that yields are similar there.  That would say to me that nobody's farming hot springs for T. aquaticus.