I'm starting next week at a company and the kitchen has only instant coffee. I'm a coffee lover and I want to bring an espresso machine to the office.
What do I need to consider before I bring a machine into the office?
For what it's worth, I am a coffee lover as well. When I first got to my place of work, they only had a terrible vending coffee machine, that made disgusting coffee (socks juice as we french affectionately call it).
I work in a big open space with a little over a hundred people working around me. It was almost impossible to get my own machine without being either the outcast (coffee breaks are the main socializing points during the day) or forced to share, which, with such a high number of coworkers, would've deteriorated my machine in a matter of days.
Instead I talked about the issue to my coworkers, convinced them to chip in, and got a Lavazza espresso machine that does above-par coffee. It is not the "expensive gourmet stuff" (obligatory Pulp fiction reference) but it tastes okay, is affordable and can handle the load of dozens of coffee per day. It now sits in our corner of the office and has drastically improved the life of about 10 developers :)
My point is, you cannot assume there's a rule, and don't expect to get your answer from a website. Go to the office, find out how many coworkers will be around you, what their coffee-drinking habits will be like, and whether they'd be willing to chip in for a new machine. I'm sure a lot of people around you are bothered by the instant coffee, so it shouldn't take too much convincing.
For the permission to bring it, again, it depends on your office environment. In this particular case, I find that it's often better to ask for forgiveness than permission. A boss might say no to a cumbersome espresso machine, but far less likely to be mad once it's here, as long as he gets to enjoy better coffee as well. Very important: this is how it works at my office, don't take my word for it. Go to your office, find out what it's like, and make your decision then.
Finally, I get the impression that you're considering bringing your own machine and not sharing. I may be mistaken, but if that's the case, don't. As I mentioned before, coffee plays a very crucial role in office socializing. You do not want to be the new guy who brings his own coffee. This guy doesn't usually blend well with the rest.
As rahmu says, consider the likely wear and tear on the machine, and the social ramifications. I work in a relatively small office (20 people in my immediate work area, 100 over all) and I brought in my personal espresso machine in the first week. Since I was willing to both teach people to use the machine and share some coffee beans/have everyone chip in for coffee, it was actually a huge social bonus for me. In general, my experience has been that if you bring in some small creature comfort to the office and are generous with it, then people will be very happy that you went to some effort to make the workplace nicer.
However, know that the machine probably will take some damage. People have broken portions of mine more than once, but my coworkers have always voluntarily replaced the broken parts because they appreciated having it. If you are comfortable with the likelihood that you will take some small losses, either in wear and tear on the machine or in people using coffee they don't chip in for, then go for it. However, if you aren't going to be able to take that gracefully or don't want to share, find some less obtrusive way to have access to good coffee. I will note that there are some great tiny, relatively cheap espresso machines available like this one I have that might make risking a machine at work more viable.