Knowing WETA these were either made in house, or were extensively modified if they were sourced commercially back in 2007, so, odds are slim you will find an exact match commercially available today.
I would recommend looking for khaki or tan "Dump," "Admin," or canteen pouches as they should have a similar shape. Also look for British or New Zealand army surplus if possible, as with WETA being based out of NZ, if they did use a commercial pouch as a starting point, those might be likely candidates.