Can you give some pointers on tracking these down? I found this WYSE one in a video linked below, but I can only find a couple overpriced ones on ebay.
I bought mine at a Swedish online auction site. I suspect eBay is the place, but unless you are not getting an AT converter with it I would not pay more than $20.
If you find an old Packard bell with a 1.25 unit wide escape key it is certainly a BTC board. That is how I found mine. 25sek (about 3 bucks) without an AT converter.
Just look for retro keyboards. The 1.25 unit escape key is the first thing to spot. Then make sure it is the dome-with-slider one and not a foam-and-foil (which are certainly degraded beyond use by now).
Personally I think the future of tactile keyboards is rubber domes and either light-based sensing or EC style (like topre). No friction, yet great tactility instead of the almost-linear switches like cherry MX brown.
Reading "No more Mr. Nice Guy" was like someone peering into my brain and describing it. I'm cautious in taking the psychological explanations for granted, but the behaviors themselves were scarily accurate.
https://www.youtube.com/watch?v=TK7oaCQ-SGM