Over the years I've collected quite a number of focusing screens - mostly from different cameras that have come through my hands but I've also picked up a lot by rummaging around in the factory QC area while in Germany and bought ones on ebay going as far back as 2004 when I first my first Rolleiflex SLR camera - a 6008AF. I've even had some made myself. Since I stopped selling Maxwell screens (too much hassle, too expensive, virtually identical to the High D screens) a lot of people have asked about screens so I've started to go through my screen box and list them. I've also gotten in from the factory some NOS High D first Generation screens for both the SLR and TLR screens.
I've learned a few things about focusing screens over the years - focusing screens are personal choices, not one is always best. Some people prefer one style or another or swap out screens for the project - macro, indoors, architecture/landscape, etc. It's really cool how quickly and easily the screens can be swapped out in the Rolleiflex SLR cameras.