One important aspect to recognize is that when you compare amps from different companies you are comparing different house sounds. Given we all have different values, we will prefer different house sounds more than the particular implementation.
So, say I like Audio Research’s amp sound more that Boulder. A $20K ARC amp will sound better than a $40K Boulder. But if I liked the Boulder sound my choice might be exactly the opposite.
Within house sounds (companies) the sound quality improves with greater price (let’s assume high end stuff > $5K), I don’t think I have ever heard a violation to this generality.
So, I think when you think about your experiences, you need to incorporate this into your analysis. Assuming you are not just biased against high cost. This will either leave you with too little data to draw a conclusion or likely that price / performance has a direct relationship. The slope of the line formed with these two variables will depend on how much you value improved sonic quality.