Well, I think that to be hi-end, it should reflect performance, but that is in an ideal world...
The only components which seem to really benefit from investing more money[and even this is limited to a certain extent, and is not a rule, especially if you build yourself from a proven solid design, or are able to originate a good design yourself] are speakers and room acoustics. The rest of the stuff[sources, amps, etc.], with modern technology, is functionally ideal at low to moderate cost. More money with these things tends to buy better cosmetics and physical build quality, not actual functional performance increase of audible relevance.
-Chris