The $30 departure fee is way old. It is currently $39 per person and included in the price of most tickets. I just checked AA and Delta to confirm the amount.
Sint Maarten - Airport Departure Tax (SXM) (FH) $39.00 USD (From the Delta site)
AIRPORT DEPARTURE TAX (SINT MAARTEN) $39.00 USD (Fromthe AA site)
Too bad Flamingo and Royal Palm can't have accurate information. It would make me question if any of the other information is accurate as well.