The new-build Lancaster/Stirling/Fortress fuselage projects so admired on the forum might show the way ahead, as they can be started in a smallish space, , but with scope to grow if resources permit. £50K would get you off to a very good start.

I think a reproduction walk-through Sunderland fuselage exhibit( like Hendon) with be far more meaningful than a very broken corroding lump from the sea-bed, which to many visitors will probably only ever look like a load of scrap. You could spend an awful lot of money, and end up with very little.