Assuming I can correctly understand the right tickets for using the BKK Budapest public transport system, I'm planning to take the 200E bus from Budapest airport to Kőbánya-Kispest, then the metro onwards from there.
However, a possible wrinkle is that my flight is set to get into Budapest fairly late, and even if everything goes well I suspect I won't have got my bags and cleared immigration + customs until at least 10pm. If there's any delays or problems, I could well see that being 11pm+.
That makes me wonder - how late does the 200E bus run? Does the last bus get you in before the last metro leaves, or could you be stranded at Kőbánya-Kispest for the night? And other than taxis, are there any alternatives for late night departures?