I know there is probably heresy to say here, and I'm not sure I will take my own advice here... but here it goes...
I have spent a lot of time getting jets, removing carbs, installing carbs, getting more jets, removing and installing, etc, etc, etc... Jets are cheap, but I think I am up to maybe 8 mains and 4 pilots... and would have more pilots but nobody local has the right sizes in stock. So even at $5 to $10 per jet, I'm pushing $50 to $100. Having done all that, I now have a KDX that... sort of mostly runs pretty good.
Don't get me wrong, the difference between where I started and where I ended was day and night... but I still have a little burble at WOT and high RPM. Since I had the pile of jets and was getting good at swapping and testing, I was simultaneously trying to tune another friends KDX-200... with similar work, I now have his running really well everywhere but "get a bog when you whack the throttle from very low idle".
So again, far better then where it started (which was bog anytime you whack the throttle from anywhere), but it's still not perfect.
I don't doubt I can eventually tune both out, hopefully without screwing up some other aspect of the jetting that is currently working so well.
So I chat with my local friendly dealer, and he says that they can generally tune them with about an hours work (which I am guessing is $65 or so). They said they try and keep the jets in stock, and just charge you for the ones you need, not all the ones they tried. And most importantly, they tune the bike with an exhaust gas analyzer and a ton of first hand experience.
Until you try it, you don't realize how easy it is to fool yourself. Did that last change wake up the top end and make the thing a monster? Or just ruin the bottom and and make a mediocre top end look good by comparison? Did you let the bike warm up enough to get it right? Is that bad jetting, or a fouled plug from the previous test (which was even worse jetting)? Are you rich, and need to go leaner, or lean and need to go richer? How many tests with how many jets to you need to really know?
So play with the jetting for fun and experience, but having done all that, I suspect I will still be taking my bike to a local expert (with an exhaust gas analyzer) who can really dial in a perfect baseline.
I suppose he may give it back to me with some minor flaw and he won't be any better off then I am... but I'm guessing that won't be the case...
It will be nice when the day comes that you can get an affordable home exhaust gas analyzer. They are starting to appear, but the ones that I have seen are based on car O2 sensors, and seem fragile, limited in what they can see, and still pretty expensive.