"Are you planning a trip to Budapest and this will be your first visit ever? Do you need up-to-date information about public transport?
Then look for the Customer Service Points of BKK Centre for Budapest Transport at Liszt Ferenc International AirportÂ’s Terminal 2A (daily 8:00-22:00) and Terminal 2B (daily 9:00-21:00). English-speaking attendants will be at your service with useful information on transport and tourism. Almost all types of tickets and passes are available for purchase at the airport including the practical 24- or 72-hour travelcards especially designed for tourists. Further information about the hours and operation of the Customer Service Point
Please note that front-door boarding only policy is now in place on bus 200E serving Liszt Ferenc International Airport. Single tickets are on sale at the following locations:
•BKK Customer Service Points at the arrivals level of airport terminals 2A and 2B
•ticket offices at the bus terminus next to Kőbánya-Kispest metro station:
•near the exit of metro line M3, in the corridor leading to the MÁV Hungarian State Railways station
•near the passenger drop-off site of bus 85
Additionally, single tickets are available from the driver onboard the bus at the price of 450 HUF."
http://www.bkk.hu/en/tickets-and-passes/prices/