Originally Posted by Henry III

Just checked again on Expedia: the fare rules are indeed bizarre! If you do the 'same' search but add a third segment (CDG-AMS, which you then just throw away), the prices drops to £322 ... and you end up on the same (2) flights! (So you search multi-destinations, direct only, for AMS-BUD, then BUD-CDG, then CDG-AMS.) This is clearly not as cheap as other options mentioned, but it's far more reasonable than 1,500 quid, it keeps you in the AF/KL fold and avoids (long) train rides. (And also avoid the need for 'nested' returns with two throw-away segments.)

-- Henry