Personally I've learned with certain items you're better off spending a bit more than you want to on something that you'll get loads of wear out of. I used to buy 25 topman jeans every few years and they'd start to fray and discolour so quickly! Ended up spending 40 on a pair of indigo Gap 1969 jeans that I practically live in. The same way my 35 ASOS desert boots lasted about 10 months before falling apart, whereas my Clarks ones are still in great condition.

I agree on the whole going cheap on accessories/basics like white tees you'll most likely wear jumpers/cardis on top of. As a student myself I know how tight money can be, so the process of building a new wardrobe will be a slow one I'm sure. Not sure what the temperatures are like in New Zealand, but I'd start out with a nice slim fitting pair of jeans, one or two jumpers/cardigans you'll get lots of wear out of and build from there. As I mentioned before, I recently bought some Clarks desert boots and again, slightly more expensive than I'd have wanted to pay but I wear them all the time. I rotate between those and a pair of New Balances I love, so no need to spend a huge amount on loads of cheaper pairs of shoes that'll fall apart in no time.

I think ASOS is a pretty good place to start, you can get some jumpers for 20-25, same pricing for shirts and by the time you've spent about 200 on jeans, jumpers, shirts and a pair of shoes/trainers you think will work with a lot of your clothes, you'll be well on your way.