It doesn´t get much rarer than this:
http://cgi.ebay.de/EKO-COMPUTERHYTHM-SU ... 3cb52d9d50
Mind you, this is not the prototype, and it´s not one from the first batch of units made (which was only three or four instruments, according to Chris Franke).
Snap it up while you can,
Stephen.
BTW: It´s not mine, and I´m not affiliated with this sale.