I bought it at my local paint suplies shop, the brand in question is 4CR and they do it with a machine they have there, as far as I know, you insert the colour code in to the machine and it mixes inks to achieve this color and then water + some other stuff, puts it in a can (if you use spray cans) or in a container (if you use compressor). It´s essentially sold as paint for cars, so if you ask for such at your local shop, that is the ideal kind of paint for this kind of job, not only the acrylic part, I.E. not afecting heatsink capabilities and such like plastic paints, but also the durability and strenght of it, but of course, you pay the price, it´s quite expensive, it works out a lot cheaper if you use a compressor as that way you´re not paying for the aerosol and can which, is, in my shop´s case, 35-40% of the price.
Within this there´s several types, I´ll translate as best I can, but this may not be the right names in english (I´m used to their spanish counterparts), mono-coat is as basic and cheap as it gets in this area of paint, but it requires a primer before it and lacquer after. Dual-Coat requires no primer, but the surface must be sanded and perfectly clean, it also requires lacquer, Tri-coat is the same as Dual-coat but it has more componentes, depending in the type, to achieve for example a metallic effect like on modern day car, other effects inlude pearl, and so on, it does however, still require lacquer. There are some variations that already incluce lacquer, like for alloy wheels, I´ve never trusted these though, as it´s never as strong as aplying lacquer afterwards.
