Almost never negotiate either, take it or leave it! I am in no hurry.
Besides music instruments and gear is not something that is worth investing your time in.
It always takes far too long to get rid of, that is also why I have stopped being in a hurry.
People talk alot and do little!
I understand your approach, but mine is different. I agree that it isn't worth investing much time in selling musical instruments and related gear, or cars or whatever. For that reason I am in a hurry to get it done. I do a little bit of research before listing the item for sale, and I price it almost exactly at what I believe to be fair market value. Serious buyers recognize that immediately, and they act quickly to avoid missing out on a good deal. I have sold several guitars and amps in the past ten years, and they sold very quickly. Time is money to me, and I am not going to waste $100 worth of my time trying to sell a $400 amplifier.