A word of warning. We were advised that a taxi from Phuket airport to khao lak would cost at most 1500bhat so we didn't bother arranging a transfer with our hotel. Mistake. We were charged 2500bhat! All the taxi companies were charging the same - £50 for an hours journey! Annoyance not helped by our driver who overtook on blind bends etc.
Be warned and avoid the airport taxi mafia at all costs.