It's worth whatever someone will pay you for it; I'd guess around $500. Are you trying to sell it, or get it working? To upgrade it to Windows and Mach3, which is used by current Taigs, you'd need to upgrade the controller box so it's capable of handling step/direction inputs. Newer Taig mills have also gone to an ER16 spindle; yours probably uses the older proprietary collets. And Taig CNC mills now come with a better motor.