Hi -
Actually, the tourbillion isn't a complication at all, since it doesn't add anything to the time keeping qualities of a watch. A complication means that you have a date function, a day function, moon phase, other kinds of calendars (central hand with a pointer to the dates listed on the rim), UTC functions, etc etc etc. All complications are frosting on the cake, as it were.
The tourbillion basically is the most complex addition to the basic watch that you can make: it improves the core time-keeping behavior significantly, basically removing the effect of gravity on the watch by moving the balance around while it is beating. Ideally it rotates once a minute on one axis, once an hour on a second axis and once in 12 hours on a third axis, with the axis in question determined by the design of the watch, which can determine if the x, y or z axis shows the greatest deviation from the average (this is the axis which is then assigned the fastest turning).
Now, as you can imagine, this sort of thing is fiendishly devilish not only to design and actually get to work, but is a monstrously complex thing to build. One watchmaker I know built a 100x model of his own tourbillion design as an exercise to get his master watchmaking certification in Germany; he almost had a nervous breakdown doing so, the damn thing was so complex.
Now this explains why they are so damned expensive to make: first of all, you have to make a cage within which the balance wheel will move, and this needs to weigh virtually nothing in order to itself not exert any meaningul impact on the time keeping ability of the watch. This means that you cannot automate the manufacturing (yet!), but rather it's done with highly skilled manual labor.
And that is where China comes into play, since that is what the Chinese watch industry is developing: highly skilled manual labor that costs, in comparison to a master Swiss watch maker, virtually nothing (but still more often than not a good living wage in China!); other than that, a tourbillion is a tourbillion is a tourbillion.
JohnF