Dragoon

Why is it costing almost the price of the whole SuperNova for just the barrel?

Is there anywhere online that I can order parts and accessories for my SuperNova? This site lists them but does not have a way or ordering them, nor could I find any site that sell the parts. Im looking for the Supernova Pistol grip stock and the 18.5" Barrel but I cannot find any place to order them online.