I have witnessed it a couple of times already. And not just from people that you would consider "keyboard enthusiasts".
I have seen people bring in and replace not only keyboards, but monitors and mice as well. I do not see a problem with it. What employer would want to discourage his employees trying to be comfortable and productive?
I work in different locations and have a keyboard everywhere. Typically, no one mentions anything if you do not use a keyboard that stands out in the way it looks or sounds. My realforce do neither really. The only thing people ever respond to is when they spot the hard to read black on black dye sub. I wanted to get black on beige for the office to make it blend in, but happened to stumble on only black on black in classifieds each time.
Some might think it is a little crazy to invest in a keyboard to use at work, and pay even more money, like the keyboards you have at home are not expensive enough. Though personally I think it makes sense. I spend a good 8-10 hours of every weekday behind the desk at work. I get more typing done there than I do at home (or at least as much). So to me it makes all the sense in the world to invest in a work keyboard. You buy it once, and from then on it is what you will be using for years and years to come. You may only need to buy a few over your entire career, and in return you can always have a pleasurable typing experience for the rest of your life. To me that is easily worth it. Especially if the keyboards you use at work are a particularly heinous ISO layout, short left shift, sticky coating, slow-to-rise-when-bottomed-out, kind of Hewlett Packard keyboard. The fact that I have used ANSI my entire life, and most workplaces in Holland use ISO is reason enough for me.
One tip for work. If you know a model of keyboard that you like. Try to get a used second hand one with some wear and tear. It may no longer look as pretty, but it can typically be used for many, many more years. It is a good way to get good value out of a work keyboard where you do not care what it looks like anyway.