I think $100 would be a reasonable price to pay for a keyboard that you use for many hours every day over several decades. The Textblade seems like something that I'd use in short intervals here or there for a year or two.
Keyboards and mices from Microsoft and Logitech used to cost around $20-$30 and were of such a high quality that MTTF was about 10 years. Nowadays their products do not meet my needs (no 1990s/2000s traditional business style, only fancy form factors) and are overpriced with lower quality.
Most keyboards from <1990 that have been treated reasonably well are still be in good working order today (or are at least repairable). It’s only really the last 25 or so years that keyboards have been on a downward cost/quality spiral.
My favorite freestanding desktop keyboard is still the original Macintosh Extended Keyboard[1] (the 2 is ok, but not as good as the original). I still have one in use on my linux machine. It requires a ADB to USB converter, but it's HID and so it works with anything. That keyboard is from the 1990 timeframe, so it's about 25 years old now and still works wonderfully.
