Amount:
20 - 1000 AUD
Does that mean theyre selling 20 bitcoins for 1000?
Look more carefully, you'll see another area where it says "Price:" that will have the amount they are charging for each bitcoin.
It means they are selling bulk, you can buy a minimum of 20 bitcoin and a maximum of 1000
Actually, it means you can by a minimum of 20 AUD worth of bitcoins and a maximum of 1000 AUD worth of bitcoin.