You may not know it by name, but you know what it is. That hulking beige beast of a 101-key keyboard at came with every IBM PC from the '80s to the mid '90s, the one with real mechanical keys that have real travel and give a satisfying click with every keystroke.
Neither IBM, nor Lexmark, nor the Chinese IBM-PC successor Lenovo makes these any more. Places like www.clickykeyboards.com have them for sale when they can score sets of them from the dark recesses of PC resellers' warehouses. Used parts outfits like MCBIA.com hawk "like new" Model Ms. Rare new-in-the-box Model Ms can go for $150 and up. Even used ones are $50+ when you count shipping. A far cry from the $5 Malaysian keyboard that comes with a new Dell or HP.
Why pay this much for a keyboard? Because it is simply the best keyboard ever made. I made a convert of my wife years ago. I've been using mine for almost a decade. matociquala says that she's banged out fourteen novels on hers. The only problem she's had was a sticky left ctrl key (which was the spark for our conversation). And you know what? She fixed it. Try to fix anything on a modern all-plastic rubber-membrane keyboard. Hah! You can type faster, with fewer errors, and less fatigue on a Model M than any keyboard I've ever seen. And we three are not alone in our devotion.
I have a small cache of Model Ms in case mine gets ruined or ever breaks. Happiness may be a warm gun, but true love is a superior keyboard.