Originally Posted by sokolov

Budapest-Vienna, Vienna-Prag are definitely train or bus distances. There aren't many flights and certainly now low cost flights.

Train tickets are very cheap if booked a while ahead. Vienna-Prague by train is available from 29 Euro I think and buses are even cheaper.

You won't be quicker with a plane if you factor in the time it takes to get to/from airport, the wait at the airport etc.

Good travels!