By Public Taxi Meters from Suvarnabhumi Int. Airport:

Upon your arrival, look for the signs to metered taxis at level 1 near gates 4 and 7. The taxi costs including the highway toll is (maximum 250 Baht) depending on traffic condition. Please mind, you must pay for the toll way yourself, directly at the toll booth. There will be an additional surcharge of Baht 50 to the meters for travel from the airport. The traveling time is around 20 minutes depending on traffic condition.