There are actually different 'ratings' of fakes - i.e. cheap ones to really decent ones.
Before I started buying proper watches I had a contact in China. Even the best Swiss watches are made from Chinese parts and assembled in Switzerland.
This guy used to have contacts in all the factories out there and had them smuggle parts out for his experts to build. They weren't cheap (around ?ú300-400), but were exact replicas of the originals - the only fake bit was the serial number.
I've got a couple of Tags from him stored away that still run when I dig them out.