Well, there is the angle of 10 years parts availability that the EU requires (I don't have a link to prove that though), and I wouldn't think that covers price control. BMW can charge whatever they like. Oh hang on, they already do.
Having one spare in the garage does control the price, and it's probably still got reasonable value in, say, 5 years time. But like all 'investments' it does tie up your dosh somewhat.
