Cotton on has been my saviour for tops. They are stretchy, you can layer them, they have thick straps so bras arent a problem and they are only $10.
As for pants, i have a few elastic waisted skirts that were already in my wardrobe and i have a pair of cargo's from P/patch and some jeans from there also. I think it is worth investing in the basics as you are probably going to be wearing them for about 1 year all up - unless you are lucky and fit back in your small clothes earlier.
I brought quite a few things from an american store destination maternity - the motherhood brand. Because of the seasonal difference their sale items are perfect for the season we are in/going into.
Oh I forgot to mention the website Moms In Mind do some really nice transitional clothes that go from maternity to breastfeeding. I bought four breastfeeding tops from them at around $25 each (they are in Singapore & the exchange rate is pretty good).
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