How many zither makers are still working? Where does one get a new zither?

You can't go wrong with Horst Wunsche. The website is still up and these zithers are really top of the line. I don't know if the Meinel shop is still open. Ulrike Meinel took over from her father, running the shop with her son. I'm sure there are folks on this list who are more familiar with this than I am.

Ken Bloom
http://www.boweddulcimer.org

I agree with Ken, Wünsche makes solidly-reliable instruments. I visited their factory the year before and enjoyed the experience. This year I bought a nice travel zither from them.