From De Wallen: Amsterdam’s Red Light District artists’ book by Daniel D. Teoli Jr.
Blue lights signify the prostitutee (prostitute) is transgender, red lights are for female. A mix of blue and red lights advertise the transwoman take on all comers…male or female. Although some transwomen try to pass for women with red lights only.
The prostitutes have their own union De Rode Draad. (The Red Thread) Although many of the prostitutes don’t join the union. Since prostitution is legal, escort services are very upfront with their services.
An example agency: http://www.societyservice.com/home/
Rates are €750 for 2 hours. There are many brothels and sex / swinger clubs located throughout the Netherlands. Some advertise a ‘porn star’ service where they will film you in your own porn video with a prostitute.