I'm quite aware that prostitution in the Netherlands isn't the best work environment ever, allthough I admit I don't know anything about it except general knowledge. And I join CountArach in not understanding your arguments at all- for starters,

1) why should legalized prostitution be more expensive? It shouldn't be, unless it's seriously overtaxed
2) for those prostitutes operating outside the law, why would they be worse off if they have competition from legal prostitution?