The devil is in the details. Take some time and look ridiculously up close at gen dials and really soak in the minutia, then compare to the various rep options: minute track and distance to dial markers, shapes of dial markers, lume color and application, text font, thickness, serrifs, color, and position on dial, finish of dial and its edges, baseplate condition and dial feel, etc (I could go on).
If you are OCD enough you will see why some charge more, some less, and you have to pick the level of accuracy vs cost that you're comfortable with for your build. And if you are reeeeally OCD enough you may even be able to spot some of these dials in Gens that are for sale on various platforms... buyer beware
My favorite dial that I have is an older MQ Red Sub, it's just unbelievable the level of detail put into that and its better than what he has available now. This dial isnt even in my best build, but I'm happy where it is, for now.