There's no point buying DisplayCal. If you purchase the X-Rite model, or a Spyder unit, they both come with the necessary software to calibrate and profile your monitor. You'd just be spending money on a separate software package you don't need.
No one is being ripped off. Apple doesn't sell or include the necessary hardware to calibrate/profile your monitor any more than Windows computer makers do. Most people don't need perfectly balanced monitors. If all you're using it for is browsing the Internet, writing letters and working on spread sheets, it's a rather pointless expenditure. Meaning, most people would either never use the hardware, or throw it away.
Rule number one: Never calibrate your monitor to the highly idiotic default of a 6500K white point. NEVER! Look at an image of a sunny day on a monitor balanced to 6500K and then look out your window on a sunny day. Is anything as blue as your monitor? No! You need you monitor to be gray. Or more precisely, what we as humans consider a neutral gray. It's impossible to make anything look neutral on a 6500K monitor since the monitor itself is heavily skewed to blue. Nothing you can do in Photoshop or in any other app can overcome the monitor's fixed, bluish "gray" balance.
6500K is the worst default in computer history. Basically, someone thought it would be a great idea to continue the intentionally incorrect color spectrum of the beginning of color broadcast television. And then we have the joint venture of sRGB by Microsoft and HP to drive the ugly default home.
Yes, this whole 6500K thing drives me nuts (can you tell?). As someone who has been in professional digital color and retouching of images for about 37 years, I can't understand why the computing industry insists on using this blue balance as a default. What everyone should be using is 5000K. It's the default in the printing industry for a reason - because it's neutral gray. Professional color viewing booths are also 5000K for the same reason.
It does no good to push you to get something like an X-Rite unit without explaining why the Calibrate function is entirely useless. Biggest reasons are one, all monitors drift. With today's flat screen monitors, it's almost always towards a pink cast. There's nothing you can do to stop this aging of the monitor's colorants, other than recalibrating/profiling every few months. The other is Calibrate has no clue whatsoever what color the monitor is projecting. When you enter Calibrate, it defaults to a what it thinks is a perfect 6500K, 2.2 gamma as the starting point. Trouble is, the monitor will continually, throughout its life, only get further away from those values. So anything you do eyeballing color is meaningless. You're seeing one thing visually, and Calibrate thinks you're seeing something else by how you move the adjustments around. And then from there, it builds an equally useless profile based strictly on your calibration adjustments. It simply starts with fixed Lab values for 6500K and mathematically moves them according to your changes. All of this without any idea what your monitor actually looks like. It's rather like putting a blind man on a pitcher's mound and telling him he needs to throw a strike every time, without even telling him which direction home plate is.
When you use a colorimeter/software product, you have a device that is directly and accurately measuring your monitor's output. When it's done building the calibration and profile values (they're both stored in the one completed .icc profile), the OS then knows exactly what your monitor looks like. Gamut, color range and everything else related to the process. No guessing or inaccurate values.
It sounds like your work is for printing, as you mention CMYK values. For that, you would want to use 5000K and a 1.8 gamma. A 2.2 gamma is standard because that's the point just a hair above where the human eye can no longer distinguish one near black color from another. It's 1.8 in the printing industry because it's a far more accurate value to simulate the response of what you can print. If you were to try and print a 2.2 density on paper, you'd soak it and the paper would ripple.
