What makes you confident of this?
Hollow body instruments are another story, but solid body electrics are essentially simple wooden sculptures that you bolt hardware onto. The main difference you’ll notice between any two necks is the shape its contoured to, and the finish that’s been applied to it. It doesn’t cost $1500 to reshape a rectangular neck blank, drop a truss rod in it, slot a fretboard, glue it on, radius the fretboard, install frets, and apply a finish once your done.
Now, a company might say “we’ve cooked up 15 different setting for contouring necks on our CNC machines. People really seem to like necks contoured with setting 14, so lets charge way more for guitars with that neck”. But that boils down to personal preference.
The presence or absence of reinforcing rods, and the grain of the wood relative to the shape of the neck are the things that will influence “neck stability” the most. In general, quartersawn necks are more stable, but many guitars that people pay an arm and a leg for have flat-sawn necks. Flat-sawn necks can vary widely in how the grain pattern lines up, but I doubt you’ll see particular care taken on that unless you’re buying a custom shop instrument (much more $$$).
The other thing is that there’s still a tiny bit of variability in mass-produced solid bodies and necks, so there can be slight differences in how well neck A fits into neck pocket B, but unless you’re looking at an absolutely terrible fit, I don’t think it will matter much. It’s possible that quality control at a company will check for things like that and remove any bad fits from the “sell these for a higher price” pile, but not necessarily.
Then you get into really esoteric stuff that’s of questionable benefit. PRS claims that they shape their USA necks only a little bit at a time over the course of something like a month or two, with the idea that any changes in the shape of the wood as it “resettles” or acclimates to the humidity in the factory will get smoothed out better, and the neck will be less likely to move again afterwards. It sounds nice in theory, but I’m skeptical about how much real benefit that would have.
Another thing to consider is that “EXTREME!!! neck stability” is mostly something you need to worry about if your guitar is frequently exposed to sudden changes in temperature and/or humidity (e.g. if you’re a musician touring between different regions of the world). For someone mostly staying in one region? Not so much.
And if the main symptom you’re worried about is “tuning stability” it’s very likely that the problem lies in your nut, your bridge, or your tuners, all of which are replaceable for modest prices (though you can pay extremes if you want to). I think the vast majority of tuning issues come down to the string binding at the nut, which can be remedied by 1) checking that the nut slots are shaped properly and free of burrs, 2) adding some kind of lubricant to the nut (a classic DIY lube is graphite from pencil led, either by itself or suspended in a bit of petroleum jelly) 3) replacing the nut with either a roller nut or a self-lubricating nut. While replacing a plastic or bone nut with a self-lubricating one (e.g. Graph Tech TUSQ) is a fairly simple operation, if you’re going to do it yourself, look up some tutorials online first for tips on how to do it without accidentally damaging the fretboard. I think Dan Erlewine (of stewmac.com fame) has some good videos on it.
Edit: Most often the differences you’ll notice between an expensive off-the-rack guitar and a cheap off-the-rack guitar boil down to the amount of labor that was put into final fit and finish, mostly the fret work. Even expensive guitars can have sharp fret ends after they’re shipped from one part of the world to another. People on the internet seem to obsess about whether a new guitar has sharp fret ends, but they’re inexpensive to remedy and even expensive guitars can have them, even if they were dressed perfectly when they left the factory.
The main things to worry about when you’re testing a solid-body guitar off the rack is whether the neck, the pickups and the bridge are aligned properly, whether the neck is warped, and whether any of the frets buzz. If I’m seriously thinking about buying a guitar, I do a full-step bend at every fret on every string to check for buzz or fretting out (just check first that there’s some neck relief, but not a ridiculous amount of neck relief: too much neck relief can hide buzzes that will appear once you reduce the relief to a reasonable amount).
I wouldn’t buy a brand new guitar that truly needed a fret leveling, but even most cheap guitars don’t. Also, any risk for post-purchase warping of the neck wood is mainly with necks that are unfinished or only oil-finished.
Thanks man. I tend to write a lot, so the occasional emphasized bit probably helps.