If it's known at all outside Germany, it seems that Kibri is primarily a toy company specializing in dolls, models, and particularly model trains.
So maybe this set of c. 1960 Kibri, Kindler & Briel modular play furniture that's coming up for auction on June 23 is a highly unusual find. Which is about the only way I could see bidding at least EUR700, plus a buyer's premium, for these things.
The boxes are certainly nice looking and seem to be in good shape. They're all made of beech with laminate, and are pretty small--the biggest cabinet is just 52cm high, without the top, definitely kid-sized.
According to the auction house and the original brochure, the collection was called 'Aufbau-Möbel,' or "Building Furniture." While it might be modular in the sense that you can mix & match shelves and cabinets, it doesn't look too buildable, at least not like the classic maple cubes and bricks Creative Playthings sold after WWII. Those could be turned into desks, beds, and shelves, and then they could be taken apart and used to build a fort.
That said, I've never seen a nice set of 50-year-old CP building furniture come up at auction, so who knows? Maybe EUR700 is the right place to start. [If anyone has any relevant ideas or info about Kibri, please chime in below.]
Lotnumber: 084238: Spielkiste 'Aufbau-Möbel für das Kind' by Kibri, est EUR700 [quittenbaum.de via dt reader jordi]