I'll say it before and i'll say it again.
If WB wants to make a "proper" superman movie with good action sequences , i can't see the budget being any lower then 200 million UNLESS WB and/or the director decides to shoot the movie like 300 or SW ( total blue screen shoot). And even then i still think you're looking at a budget of around 150 million.
Many directors complain due to problems when shooting blue screen and it's certainly not for everyone.
Now of course given the performance of Superman Returns , many are saying that WB can basically "force" a director ( like singer...) to shoot a movie using the 300 method. But if WB decided to get a high profile director , chances are the director will still have enough freedom to do as he wishes. Take Singer for example. Before the hate he got with Superman Returns , he was quite a "beloved" director. He made a critically acclaimed movie ( Usual Suspects) and directed two very succesful comic book movies. ( X1 and X2).
SO when WB saw that he wanted to make SR , they gave him carte blanche.
Of course WB now will probably be looking very tightly at the budget increases etc. But imagine if suddenly Christopher Nolan goes to WB and says to them " Hey guys , i wanna do the superman sequel".
Do you honestly think the Chris Nolan is gonna agree with these studio demands if the exec. say this :
" okay chris. But here's the deal.
1 We don't want to budget to go higher then 150 milion
2 To keep the budget down we're gonna shoot the entire movie against a blue screen. "
Think about it.