When in Budapest, the 200E ticket can be purchased from BKK Machines,which are purple in color.
These are general ticket machines and all sorts of public transport tickets including the 200E bus can be bought from here.
It is possible to buy all sorts of tickets and public transport passes from BKK machines.Ticket Vending machine is also 3 min walk when you are coming out of the Budapest airport.
You can buy single tickets,transfer tickets as well as day passes from the ticket machine.The machine accepts cash in HUF while debit/credit cards are also accepted.
