I know this is an old question, did you try the Zig-zag website:-
http://www.zigzagtour.de/index2.htm
They have an online shop. The system is quite expensive and American friends say that if you can find a pair of shortish skis in the garbage with a wood core, cut them in two with a saw, fit two metal dowels and some clips from a hardware store and you can make your own system. Obviously not good for skiing on but ok for approach walks.