Like everyone else said, pillow cases and extra tubs make excellent carriers. If you're in a rush, I wouldn't even bother with extra cases. Just stuff all your BPs into the same sack. Maybe prepare a kit that has food for all your other animals that you can grab on the way out. If you can't pack rodents for your snakes, I wouldn't worry too much about it. They can last a few weeks without food in case of an emergency.
I would also stock up reptile shipping heat packs too just in case you loose electricity.