The Florida ivory millipede, C. spinigerus, and it is the practical native alternative for anyone in the United States who cannot get the African giants.
Three to four inches, banded cream and dark brown, docile, long lived, and a straightforward detritivore. Deep substrate with decaying hardwood, supplemental calcium, and it will do the rest. It exudes the standard defensive fluid that stains skin and is otherwise harmless.
Wild-collected across Florida and the southeast, so prices are very low and supply thins through winter. Captive breeding works but almost nobody does it commercially when collection is this easy. Same permanent structure as Narceus: priced at the low end, seasonal, and not going to change.