How to get to Tulum from Cancún Airport?
At Cancún airport, ask for ADO bus company. It will get you in Tulum within 2.5 hours for 186 pesos (17$). Bus runs from 8 am to 11h30 pm, each 40 minutes or so. You will have to change bus in Playa del Carmen. The ADO bus terminal is located right down town Tulum.
You can of course opt for a taxi instead: the rate to Tulum is around 120$ (1400 pesos).