Ah, the venerable Model M - now that's a keyboard you could kill a bear with, without even scratching the keyboard :) Alas, I had to stop using that in open-space - cow-orkers complained that it was too noisy.
Unicomp still makes buckling spring keyboards with IBM's Model M (as well as other IBM) designs. They're loud as hell but feel great. http://www.pckeyboard.com/ You can ask them for Mac keycap replacements to swap out the ctrl/windows/alt keys with control/option/command keycaps. Works great on my Mac with swapping Alt and Option key functions in the keyboard preferences panel.
The IBM 5150 with model M was released in 1981. I still use the keyboard every now and then. It's a nice contrast to Apple keyboards which have no travel, no mechanical switches, and weird spacing/sized keys that float.
Here's a modern variant: http://www.daskeyboard.com (which refers to the Model M the "god of keyboards")