Nephrurus levis is the species. Put generally, the species is split into three subspecies: N.l.levis, N.l.occidentalis and N.l.pilbarensis. They occupy a large area of mainland Australia, particularly inhabit arid duned areas within most states. N.l.occidentalis occupies the most westerly part of the range, N.l.pilbarensis obviously occupying the Pilbara region and N.l.levis occupying the remainder of the range. Various texts differ in their display of range with some dumping them in an interconnecting distribution and some standing by the thoughts that they are geographically isolated from one another. Identification can be tricky amongst them and cross breeding between the sub-species will occur, thus mixing genetics up and making it more difficult to identify and preserve genetic integrity of animals in captivity.
If you after the standard species that is generally termed N.levis, N.l.levis is the more accessible however it seems to me that people are even struggling to sell N.l.pilbarensis and N.l.occidentalis. In short, it won't be hard to find animals that you are after...from any subspecies.