There is no dependable worldwide ranking that identifies one Maine Coon colour as the rarest in every population. Availability varies with breeders, country, registry rules and the way colours are described. An unusual marketing name is not proof of rarity or quality. If colour matters to you, ask the breeder for the recognised colour description and the registry used, then check the current registration policy. More importantly, assess welfare, health screening, living conditions and the kitten's development.
Paying more for a colour does not guarantee better health or a friendlier pet. Ask which registry recognises the advertised colour and whether the description appears on the kitten's registration papers. A colour can be uncommon in one breeder's litters without being globally rare. Keep a written record of the seller's claim and what evidence supports it rather than accepting a premium based on the name alone.
For product comparisons alongside this advice, see Velvet Nest and Sterling Court litter tray. The details below explain their sizes and uses.
Further reading: gccfcats.org; pdsa.org.uk.
Velvet Nest
Sterling Court litter tray
Taj-MeowHall