Rice, beans, split peas & lentils. It might feel like its not that well rounded on the face of it, but you're actually getting carbs, protein & fibre so its better than you might think. And the peas & lentils are dried so last ages, are cheap and cook relatively quick too.

As Dave mentions below adding some stock power for flavour could help to make it more interesting, or if you're going the lentils route a curry powder (if you like spices) would add variety too.

Just to add to Dave's price list, looking at Woolworths (as going by google maps that's likely the nearest supermarket):

• Red Split Lentils come in a 375g bag for $2.30 - which works out to $6.10 / kg so is cheaper than buying from the bulk bins.
• Green or Yellow Split Peas are even cheaper a 500g bag for $2.20 - so $4.40 / kg.

ETA - just a thought as well, I would guess Papakura probably has an Indian grocers (often small dairy sized) or other non-main stream grocers. Particularly the former you can often get a far wider variety of dried legumes, beans etc for a good price.