Interesting.
I looked high and low for any such comparison, but only found the camera model mentioned on the Camera wiki page on Cosina.
On that page a Cosina-made 'Ur'-rangefinder was mentioned, that was also developed into the Konica Auto S3, Vivitar 35ES, Revue 400SE and Minolta Hi-Matic 7S-II.
That does not mean that the mysterious Prinz 35 ER is similar to the Konica Auto S3 and the Minolta 7S-II, since these camera's are not similar themselves.
Any link to that auction? I looked for it but turned up nothing.