Hi, you have to ask yourself what kind of precision and budget you want to reach, it also depends on the model of monitors you use, for example NECs and EIZOs come with their own calibration software. You also have to be careful about the gamut, for example Spyders before the 4 don’t work wide gamut monitors (they will give you wrong calibration). It’s also important to remember the cheap probes are designed with presets for generic types of monitors and you might be significantly out of those specs.