Found a backpack designed to hold the P4 styrofoam shipping box on eBay last night for $25. Should be here in a few weeks.
DJI Backpack DJI Phantom 4 Drone Quadcopter Carrying Case Hardshell Handle bag
Awesome i found this one also ...Waterproof Shoulder Carrying Case Backpack Bag For DJI Phantom 4 Without Foam