We found an interesting article at utopia.de about the unpleasant topic of professional fees.
The core essence of the article is the consideration to ask the customer for his own estimation of the design´s value. In the process it divides between start-ups and established companies. 20 – 40 Euro hourly rate is not paid by small businesses and start-ups. 50 – 80 Euro hourly rate is paid by well-situated individual enterprises and bigger companies.