Bounce Box storage and Mountain House, Arthurs Pass NP
I was checking out accommodation providers in Arthur's Pass and came across the page for Mountain House YHA. Mountain House is one of the places TA walkers stay if they take a zero day in the Arthur's Pass township. They have a range of accommodation depending on your need, I have stayed here with a tramping group before and it was nicely appointed.
What really caught my interest were the details of their resupply/bounce box service.
They will hold a bounce box for you to collect when you pass through the area. There is a charge: it is $10 if you are staying and $20 if you are just picking up the box. I note that there are NO outgoing postal services from the village, so this is resupply only, not a traditional bounce box.
There is an option to resupply from one of the local cafes/store or the DOC office but the range is limited and quite expensive.
You should check out the website if you were thinking of sending a box of supplies to yourself.