White 2: http://dicksmith.com.au/product/YG5542/nds-pokemon-white-2
Pretty cheap considering Pokemon games usually hold their price. In store only. Mt Druitt had a few copies of Black 2 left but they were were stickered at $40 for some reason.
Ended up just price matching it at the EB a few stores down since staff at DSE were hard to find.
Receipt: http://imgur.com/UFXDLzN
Story wise, BW2 is a direct sequel to BW1; set 2 years after. Though like all Pokemon titles a beginner will have no problem getting in to it. Version exclusive Pokemon list: http://bulbapedia.bulbagarden.net/wiki/Pok%C3%A9mon_Black_an…
The other main difference between the two is that Black 2 contains a challenge mode and White 2 an easy mode but if you have a friend with the opposite game you can get both. More info here: http://bulbapedia.bulbagarden.net/wiki/Key_System
BW1 are also $30
http://dicksmith.com.au/product/YG4270/nds-pokemon-white
http://dicksmith.com.au/product/YG4269/nds-pokemon-black
Here's the better link
http://dicksmith.com.au/product/YG5541/nds-pokemon-black-2
http://dicksmith.com.au/product/YG5542/nds-pokemon-white-2