Wrong question.
I know I wouldn't spend £300,000 on a pair of speakers, however much I like their sound. I probably wouldn't spend £100,000. But I found their sound to be far, far better than the £25,000 speakers I have now I might do. If they were better than that I might spend £120,000.
So there is no fixed ceiling for what I am prepared to spend. Most people evaluate things in this manner, rather than fixing a ceiling.