I just saw WD Mybook Essential 2TB USB 3.0 hard drive for $139 at MSY website and it shows online that its in stock at Clayton and Malvern branches (I didn't check any other store stock). I also checked staticice and this was the cheapest option returned. This price is for in-store pickup. This drive comes with 3 years warranty from WD.
Officeworks seems reasonable at $149 (http://www.officeworks.com.au/retail/products/Technology/Dat…)
Hardly Normal is selling for $179 (http://www.harveynorman.com.au/western-digital-my-book-essen…)
Bad Guys are selling for $190 (http://www.thegoodguys.com.au/chadstone/Western_Digital_2TB_…)
Dickies are selling for $269 (http://dicksmith.com.au/product/XM1267/wd-my-book-essential-…).
JB-HiFi seems to have a good deal on 3TB USB 3.0 drive but 2TB drives have better compatibility with some fussy media players and old computers.
Samsung Story 2TB USB 3.0 is $129 pickup price at Scorpion Tech (VIC) http://www.scorptec.com.au/computer/38619-hx-dt020eb/c62