Haven't been to the Dam in a while, spending all my holidays in Pattaya.
Fancy a few days in Dam though so trying to work out the prices.
From researching a bit it seems like its about 50e for 15 mins, is that right?
Usually I take a while to finish if I can at all so this might spoil things for me

Depending on the girl, it's usually 50e for 15 minutes or 50e for 30 mins.

Edit: Made corrections thanks to gentleman below.

I have never seen a girl accept 100 for an hour. Many will do an hour for 150, especially if you're a regular, but 100 for an hour seems really low unless you're talking about maybe some of the less attractive girls around the Oude Kerk or maybe in Singel/De Pijp.

Usually in De Wallen, 100 gets you 30-40 minutes depending on the girl.