Personally, I kind of like "Kamillion" ... Makes it sound expensive!
I imagine one of the reasons for different spellings is to distinguish one manufacturer's from another (and perhaps avoid infringing on trademark or copyright law - whichever applies).
It seems most people call it Kameleon, even when talking about the same product, but from some other manufacturer. They're all based on Chromaflair pigments from Flex Products, but there are a ton of names - Harlequin (PPG), Mirage (Duplicolor), Mystic (Alsa), ChromaLusion (DuPont), Multi-Tone (Sherwin-Williams), Extreme Colors (BASF),
Fantasy Colors (Glasurit), ... my brain hurts... I'm sure there are a few more.
The price is finally starting to come down to more reasonable levels (it seemed stuck at around $500-$600 per pint for quite a while), perhaps because it's being used more by OEM's (Cadillac has several stock colors which include some of the color shifting tints, as well as a few Chrysler, VW... maybe Mercedes colors).
Very cool stuff, and great for flames, other graphics or accents.