I was thinking Fluffy, then the tentacular, flying keys, big chess board, mirror of erised. If they do include the CoS with the bathroom that would be fantastic and well worth over 250 imo. I think these sets are crucial and would really help the whole Hogwarts layout. Also I think they would sell really good. I forgot to mention we also need a Shrieking Shack.
Or they could make a smaller Hogsmiede for 250, one Hogwarts expansion for 120, Gringotts for 120 and try to make parts of the corridor or a smaller CoS into an 80 set.
IF you would have to choose what is your must buy. I am still saving for DA so thats not an option. I have the main Hogwarts builds, rise of voldemort, patronus, Hogwarts Express. Would you rather get the bus, quiditch or maybe the umbridge ecounter. Or should I go all in for the Burrow. Not sure how to proceed after getting the Hogwarts pieces. Eventually I want to get them all but I need to go step by step since just got Astronomy Tower.