Yes, these "Eco Speakers" have cabinets made from cardboard. But the manufacturer also claims they are made from "100% recycled materials," which should include the drivers and housings as well, which is laudable. And they're only $15—if you can find them. They appear to be sold out from the manufacturer's store.
If you look at Gearlog's pictures from CES, it looks like they are actually sold in stores as flat-pack. Maybe that will only amuse me, but I think that's pretty great.