It really does not pay to buy them, since even if you could find them, they would not stay bright orange unless you had specific tank conditions, gender, diet, a specific point in their age and molting cycles. normally they look like this:
The same is true of many Blue species of crayfish that spend a lot of their life not looking very blue at all. therefore it's best to invest in crayfish for their size and behavior, not for their somewhat unreliable coloration.
most people who invest in such rare and expensive crayfish are hoping to breed them successfully in captivity, thus saving the predation by man of their natural habitat; they are not looking for a display piece.