I worked with several guys who married women from abroad. Best thing is go over there and meet them, not send $.
Worst case if you go over there and she's a scammer you can meet somebody else.
But if all you want is sex with some woman wouldn't it be easier just to go to Amsterdam's Red Light district?
Or go to a bar and pick up somebody?
Or try this: www.adultfriendfinder.com, there seem to be a ton of women on there.