Eh, what standard are we holding people to? You ever shop for a used car(maybe even some rare spec of a sports car)? When you finally found a good deal did you shout in the streets and put out an ad to make sure no one else is around to make a greater offer?
~~Plus, who plays out a mental moral dilemma with a historical museum any time they want to buy something?~~
Actually I think this might be a false equivalency OP, because this isn't just any old used car. I think it's fair to at least stop and question whether this should go to some greater good or not.