Yes, to clarify. Wico themselves no longer makes those sticks. Clones of them seem to go in and out of production.
You may have to look around a bit, but they are always available, if not new, then used. You do not want to swap a bat handle onto one of them, the additional length would screw up the feel, and probably lead to wearing out the joystick early (although these things last, if you buy some new or NOS ones, then you probably won't ever wear them out).
If you are using a wooden panel, then look for the ones with the longer handles, as the shorter ones are realy only suitable for metal panels.