Option One: Make your own Grab Bag
The most cost-effective option is making your own grab bag: Get a sturdy backpack which would be comfortable to carry a long distance, then fill it with the items you need.
Remember to change the food/water in your bag at regular intervals.
Option Two: Buy a pre-made grab bag
WREMO has partnered with Grab&Go to make getaway kits available at a reasonable price.
You will still need to add personal items such as sturdy shoes, hygiene items and your own food.
Grab&Go bags are available online (Grab&Go website)
They are also available from many retail outlets around the Wellington Region.