That seems like an even worse idea. It would probably be more in the spirit of this award to base the requirement on the amount of tie-in merchandise or how much money it made rather than cost. Or they could just demand that it either be a sequel or already have a sequel contracted at the beginning of Oscar voting.
If we're just talking about budget and spectacle, in the mid-90s to mid-2000s Braveheart, Gladiator, Titanic, and Return of the King all won BP, that's four in an eight year period. Of those LOTR is presumably the best blueprint for the kind of thing we're talking about, since that one is a franchise fantasy and the others are all "historical."