I worked in a Musicstore for some years. My general rule of thumb would be that all instruments have a range of quality attributes which improve their sound and playability in a pretty obvious and straightforward manner. These are obviously different for every Instrument, but the characteristics which bring the most “objective” and significant improvements usually happen at the price-threshold from “cheap” to “moderate”.
The classic example is pressboard-wood in acoustics below 100. For just some Bucks more, solidwood becomes the standart and the sound improves drastically.
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My verdict is, that for the overwhelming majority of listeners and players (aka if you are not uli jon roth and you get by without an enchanted skyguitar from outerspace with 234 frets), there isnt much serious quality to be gained beyond the point of broadly 1000$/€. Emotional reasons are a valid argument to go beyond that, of course, but its not about sound or playability anymore.
Naturally, for everybody with my approach, there is a supershredder who claims to be able to hear which damn screws they used to bolt on the pickguard after he turned the gain to 11. I had such conversations. I dont want to object these positions, since i am just an amateur trying to play more slayer, but did i hear the difference in quality when he was using the cable with the magical runes inscripted with leprachaun-blood? No. I just heard two almost identical guitarsounds, not one superior to the other.