The IBM Model M was a keyboard was first released in 1985 as a cheaper successor to the Model F. It’s hard to imagine a keyboard more expensive as Model M keyboards cost a bomb even in those days but it’s true.
The Model F was based on a very durable capacitive buckling spring but was expensive to produce hence IBM made the Model M with a lower-cost membrane buckling spring model. At the same time, the Model M pioneered the ANSI 101-key layout that is still in use today. This keyboard was also the first one to utilise the PS/2 connector which would go on to be in service for decades.
Modern-day versions of the buckling spring IBM keyboards. I’m using their Mac-specific model. Works great.