Trade Secret is a great clothing store that sells quality brands at discount prices. If you're after cheap quality bras this is definitely the place to go! They have designer brand kids and adult clothing at decent prices, as well as standard brands for really good prices. Last week I was able to get two sports bras that normally retail at $60 for $15 each! I have also managed to get two pairs of really good quality Speedo swimwear (that you would only usually be able to find in the designer shops) for $30 each, marked down from $120. There are other Trade Secret stores throughout Brisbane and around Australia.
Check the sales racks - they are usually the best reductions. Everything in the store is reduced already though.