The $70 preorder deal at Dicksmith expired so I searched around and found it cheapest for $73.56 at Blockbuster (+ $2.50 shipping).
It says release 27/03/15 even though everywhere else it's 25/03/15 so I assume you'll get it 2 days later?
Also I have no idea how's their stock on preorders. They could run out.
Ozgameshop has it for $72.99 free shipping but they ship from Europe.
http://www.ozgameshop.com/ps4-games/bloodborne-ps4-game