Yes Mountain House products are available here I think, however the most common brand is Backcountry Cuisine. They have a variety of different single meals (around $9-$12 NZD over here) and also ration packs with a whole days food (around $30 NZD). Feel free to have a look around their website they have nutritional infomation, etc.
Their meals are very tasty and they are stocked in almost every camping or outdoor shop in NZ.
Many thanks Ryan =)
So Backcountry Cuisine eh... Mmmmmm Yum Yum~ Will give that a try!