RoboProp is right. You can't legally sell a “Proton Pack” because Sony owns that name (they probably own the design, too, but nearly every Proton Pack isn't 100% accurate to the movie). So Norm doesn't call his packs “Proton Packs” otherwise he might cop a fine or lawsuit from Sony.
I remember he used to call his packs “Ghost Catching Unit” or something like that. “Phantom Pack” sounds cooler, though

Rick