Oh, I'm so sad I missed this auction. If only I could find a gray IBM, I wouldn't have to wash my hands before I used my keyboard. No matter what I'd been doing, I could sit right down and start typing without a thought for how grimy my fingers were. And since it was made for factory floors and auto garages, I'd be using it completely authentically. Such freedom from personal hygiene is certainly worth $200!
Okay, I'm being ironic. The only reason Industrial M's seem "rare" is because so incredibly many non-gray M's were made (like, 10 million?). It's only a relative kind of "rarity".
Reality check: Changing a keyboard's color does not change its intrinsic value. I think that anyone who's willing to pay $200 or more for a Model M just because it's gray must be (a.) suffering a kind of status-mad hysteria, or (b.) speculating on the hysterical people in (a.).
I may seem like a wet blanket—but to me, an M's value comes not from something as incidental as its color, but from its ingenious, enduring design.
My wife inherited a chrome Sunbeam toaster that works as well as it did in the '50s. It even lowers the bread for you and raises the toast when it's done. It's the Model M of toasters. Such things are impressive legacies from a time when people cared about quality as much as they cared about profits.
So IMHO, to claim a Model M is worth 4 or 5 times as much because it's gray instead of beige is to trivialize the greatness of all Model M's (and yes, regardless of how much more grime it can hide).
I can sit back and enjoy the Industrial Circus, but no way will I ever covet one of these drab, inflated p/n's. If someone wanted to give me one, I certainly wouldn't turn it down, any more than I'd turn down any fine MK. And I'd probably chuckle now and then over the bizarre esteem the keyboard-kollecting kommunity afforded it. So I guess it would have extra value to me—as a comedy device.