The ProCraft backpack for the P3 will be out in a week or so. It is very cool and will be less than the DJI one, and it will look like a backpack and not a quad copter case.
Its a neat looking little pack. Although most of the time when I am filming I need many batteries and don't like taking props off each time I transport. But for little trips and short film it would be nice to take on my motorcycle.