jeewllers margins on watches vary for 50% - 200%
most mid range watches are machine produced and even worse in some cases, Tag generally buy in reasdy made components , subcontract case manufacture, assemble in far east and then pack in Switzerland to allow them to be badged swiss made
if you want to see the work that goes into high end watches this is interesting
http://www.jaeger-lecoultre.com/eu/en/manufacture/professions
So you have a jaeger-lecoultre

So if I buy a watch for £1000, 500+ of it go to the person owning the shop? Hard to believe. Whats the source of your information?