Expensive is a relative term
I believe Rolex makes more watches a year than Patek Phillipe has made in its entire history!
Most 'clockwork' watches are automatic in that a weight or 'rotor' winds them in response to movement.
Actually two companies made the vast majority of movements, Valjoux and ETA but ETA bought Valjoux in 1985
http://en.wikipedia.org/wiki/Valjoux
http://en.wikipedia.org/wiki/ETA_SA
Some of these companies customise or fine tune the movements but most of them are mass produced
The Valjoux 7750 goes into dozens of mechanical watches and makes them 'affordable' - movement's probably about 100-200 quid wholesale, the watch itself like a Breitling may cost 10 times that retail
In some cases the 'service' will cost more and they'll simply replace the movement and tell you it was serviced