The only real notable difference between them and the other guards/box vans is the inclusion of red marker lights, which surely wouldn't double the cost?
Maybe the pricing mechanics has more to do with the projected volume being only a third of that of a box van.
The degree of detail in the underfloor alone of a CP van is far greater than any box van plus vans don't have windows or marker lights.
The tooling costs for this model must be quite significant and knowing Auscisons love for high detail and paint variations, the production costs for such low volumes must be extreme.
Bring on the JCPs I say.