There is no way to establish parameters for any performance metric, never mind an overall assessment of what is high-end, or whatever level of performance. Dollars don't necessarily figure into this at all. If one's priorities in sound reproduction match a particular product's strengths, it can be reasonably dubbed the "best" even if it is modest in price.
For example, the Quad 57 speaker is so captivating in some respects that a lot of people think it is unrivalled even to this day. It has no deep bass, cannot be played very loud, and has a lot other limitations, but, I would not argue with anyone thinking it is the best speaker ever made.
There are so many different paths one can take to achieving a personal high end system and no one would agree on all of the choices someone makes. A local dealer who makes custom speakers and electronics as well as selling some quite expensive branded gear, will recommend some gear that others would find shockingly inappropriate in ultra expensive systems. For example, he recommends reconditioned Thorens 124 turntables in systems that are well past six figures in price. Even more shocking is that most of his demonstrations are done from a music server and that server is a Sonos device feeding very nice DACs. When people ask about a server, he recommends that they get a Sonos from Best Buy (he doesn't even sell them).