Speaking for myself, I have always purchased a guitar with the following criteria and their rough weight in the balance
- 60% feel of the guitar
- 20% quality (tuning stability, built quality)
- 10-15% look
- 5-10% sound
Purists could say I'm dumb, and they are entitled to their opinions, but don't forget that the tone of a guitar comes a lot from the pick-ups, which you can change. Buy a cheap guitar, put new pick-ups, and it's a complete new beast..
Also,I think that you overall tone comes from a lot of different things and the major tone driver is the amp (and cab). So for me, if you like a Dual Rectifier tone, everything that you'll plug into it should be to your liking. Ok yes, slightly different, but still.
And finally, if you add the full mix into the equation, then I honestly think it doesn't matter much how expensive your guitar is.
Oh and : All of this is based on the fact that we're talking about metal music. I think it's a different story for, say, Jazz. I am pretty sure an Al Di Meola album would sound different with a cheap guitar insteaf of his 6000$ PRS.