Value is relative. I had the Z1R with my HD800 S in use side-by-side and everytime I messed with the 800S it felt like a toy. The plastic, the itchy pads, the ridiculous cardboard box, the lack of super simple things like solid numbered notches for symmetrical headband adjustment. Etc.
And it cost me 1590 EUR. In that sense, the 1890 on the Z1R seemed pretty reasonable for something A LOT better built, light years ahead in materials and comfort (and overall physical design) and IMHO, much more exclusive.
Sound-wise, subjectivity makes it harder to value, plus they're too different to compare. Still, each is worth what you think its sound is worth.
But it's also not a night and day difference in value to me; Both have sonic strengths and weaknesses, neither is perfect, both can sound excellent when paired with the right source material (and equipment).
So I find that example interesting, especially because while handling those two (and the previous HD800) something I recall thinking is that it was about time Sennheiser came out with something refined like the Z1R both in form and function, and that is definitely within their reach.