I know some (Dutch) DJs that I can ask what they would charge, aside from a plane ticket and a hotel room. Not sure if I know any that play 80s music though.
I'm guessing booking one for nye would be a tad more expensive, but I can always ask.
Edit: ok, I just asked and one of my friends that does gigs in Amsterdam from time to time (but is no Armin van Buuren by any means) and he says that normally for a night like that and for a whole night, he would usually charge in between 2000 and 3000 euro (additional compensation for a plane ticket and hotel excluded). I guess that's a ballpark figure, he'd be able to give a better estimate depending on the specifics.
I guess it also depends on the DJ you would like to hire. But I know this guy knows his (80s) stuff, so feel free to send me a message if you're interested.