Audio is such a personal hobby I think this is the last place you want to try and impress people with how much you spend. I believe, outside the few on these forums, most view spending a lot to be more foolish than impressive.! My wife and kids included!
However, if you limit the list to the "audiophile" group I think @calvinj question is an interesting one. I would tend to agree that a well-chosen $50K retail system is a logical sweet spot for a single analog or digital path. If one's careful, buying used makes all the sense in the world. Quality/$'s in this hobby is clearly an asymptotic function and spending beyond this level I believe is because you want to and can rather than obvious benefits. As I think @mahgister points out there are so many other factors that impact the benefit of just spending dollars, especially when the incremental benefits are increasingly small.

