Just saw this and honestly, I've had such a rough time with finders myself. I wasted so much money on plastic junk for a trip to Osaka last year and it just ruined the experience. Most of the mid-range options are surprisingly let-down city... the parallax was always slightly off and it felt like I was putting a toy on a masterpiece. Quick question before I give a solid rec tho... do you wear glasses? That really changes which ones are usable since eye relief on these older designs can be a total nightmare. If you need something that feels premium but stays under $250, you should look for the Kobalux 35mm Brightline Finder (sometimes sold as Avenon). I eventually picked one up after my other ones failed me, and the optics are surprisingly close to the SBLOO but way cheaper. It's all metal and actually stays put in the shoe. The parallax lines are super crisp, which is a life saver for those tight street shots. Whatever you do, dont get the Leica VIOOH Universal Viewfinder... it's like looking through a dark, dusty tunnel and will just frustrate you while you're trying to enjoy Kyoto.

^ This. Also, I stumbled on this thread and just had to share my experience! I spent months obsessing over finding the right glass for my old screw mount and it was such a headache until I looked at the old Japanese makers. Honestly, just go with Nikon for your finders! I found one at a local shop for a steal and the clarity is just amazing compared to the hazy old stuff you usually find online. It is so bright and the metal finish is fantastic, looks like it was made for the IIIc. I took mine on a trip recently and it was a total game changer for street shooting. You get that premium feel without the Leica tax which is huge when you are trying to save for film and travel. Seriously, just get any of the metal Nikon ones and you will be set for Kyoto! They are super solid and dont wiggle at all in the shoe. Best decision I ever made for my kit, ngl.

Honestly, I've spent way too much money trying to find the perfect finder for my Barnacks and it's mostly been a letdown. The Leica SBLOO 35mm Brightline Viewfinder is the gold standard but like you noticed, prices are just stupid now. I tried to go the cheap route with the KMZ Universal Turret Viewfinder but unfortunately, it was a massive disappointment. It's bulky and the glass is often hazy. Here is what I've found after years of trying everything:

• The Voigtlander 35mm Metal Brightline Finder is your best bet. It's built like a tank and the optics are incredibly crisp.
• You could hunt for a Canon 35mm Brightline Viewfinder Metal. They're solid, but honestly, the brightlines are not as good as expected compared to modern optics.
• Avoid the plastic Voigtlander 35mm D-type Finder because it feels like a toy on a chrome Leica. I'd just grab the metal Voigtlander. It fits the shoe tight and won't wobble while you're in Kyoto... honestly the only one that hasn't annoyed me yet.