>Finally, because they are in a special class, as interns, here in NL, we can actually get in trouble with the government for paying them more than 500 euro.

Hmm...I don't think you are correct, or possibly you are misconstruing a limited, special case to generally apply.

From my own experience I earned more than 600eur as an intern in the NL, and I had classmates who earned full minimum wage as interns too (~1200eur).