Hi bro,
Since i live in Amsterdam and am a native i can give you some advice.
50 euro sounds about right for a suck&fuck, takes about 15 minutes from start to finish.
Although some girls will try and get more, they will start the money game if a price was not agreed apon beforehand which i find annoying at best. They say you can pay whatever you want, but then its 10 euros to take of the bra, 10 more to suck your cock etc etc. and before you know it you've spent more than you wanted.
So be clear about what you want to do before entering the room. Don't even think to try anything without a condom, these girls know about STD's all too well and will always use protection which is always in the room with them.
Most of the red light district is behind the dam square in the place called: The Wallen.
Just walk along the Oudezijds voorburgwal and take the sidestreets, can't miss the place because this is where the tourists go. It's not what it was like a few years ago, since then there has been a crackdown on crime that comes with prostitution (drugs, human trafficking) so many rooms are now vacant during the day but at night you should have more choice.
There are a couple of other places too, like the end of the Ruysdaelkade (for which you need to take the tram) and Bergstraat, oude nieuwstraat and surroundings (these are also in the city centre and you can walk it from dam square)
But these offer a lot less than the red light district (especially during daytime) but are more private, not a lot of tourist staring at your activities while you negotiate for a price.
also hardly any dutch girls work behind the windows (unless they are from the antilles, but these are black girls from surinam, aruba, curacao etc)
For a chance to bang dutch girls i suggest a bordello or a excort site like
www.kinky.nl or
www.sexjobs.nl for semi-pro's and amateurs.
Of course the sites are in dutch but look in the dragdown boxes for something thats called Noord-Holland, thats the province for amsterdam and since it's the biggest city most girls listed will work in amsterdam.
Most have pics on their profile and a phonenumber which most of the time starts with 06 (cellphone) (if you call from a foreign phone you have to dial 0031 and then start with the 6 followed by the rest of the number make sure to skip the 0 before the six)
Remember though these girls are amateurs and not always good looking and just in need of some quick cash most start at 100 euro's for a half hour or sometimes even a whole hour. You might need to travel a bit to amsterdam's suburbs cause a lot of them will only meet someone in their own home (sometimes husband or BF will be present in the next room for protection only) Just call them and ask about what they are offering, most dutch people speak english pretty well so it shouldn't be a problem.
And of course the younger and prettier they are the more money they will ask.
Hope this helps
good luck