I used to work as a bike messenger in Freiburg, Germany. Per Velo was and still is the biggest messenger company here. You get payed per hour, depending on how long you have been working for the company between 8 and 9 Euro.
I also worked in London at "Clockwork" (East End) Here you get payed per job depending on how far is it to deliver. You get a minimum wage of 2,50 Pounds for a standard job. Waiting time and return rides are extra. So here it depends on your quickness how much you earn. I earned an average 60 Pounds per day.
greetings, Daniel