I have not purchased a 4K-UHD Blu-Ray disc..yet.
As an Audio and Video Enthusiast I will be getting a 4K TV once HDR standards set in stone. At the same time I will buy a receiver to capable of Dobly Atmos and DTS:X.
I have already pre-ordered my PS4 Pro so if it does not have 4K-UHD Blu-Ray support by then I will be forced to purchase a separate unit to replace my existing BD-Disc player. Then once I have all that I will by buying 4K movies, but only those that have an original 4K source.
I have already spent a large amount of money on my TV and spent a great deal of time calibrating it to get the most out of HD. The picture quality of my TV is better than the cheaper floor model 4K TV's that are at Best Buy. I have seen 4K streaming and it looks terrible compared to any real 4K source. Not to mention with streaming 4K you are limited to Dolby Digital 5.1 audio.
To further explain my prefrences, even now, I will not purchase a Digital copy a console game because the audio quality is usually limited on digital downloads. The audio is usually only Dolby Digital with Digital downloads whereas the physical copy of the game will have Dolby HD and/or DTS-HD. On a good audio system this makes a massive difference in immersion.
I currently own over 100 Blu-Ray discs with many of them being 3-D. Even if a film is available on Netflix with HD or even 4K streaming I would watch my BD copy since the audio and visual quality will be that much better.
Edit: So to answer hte question, I would pay an extra $100 for 4K-UHD BD capabilites because it does matter, at least to me and other enthusiasts like myself.
