Dell has reduced the price of this monitor substantially.
Competition from a newer release model is most likely the main reason.
Might also be possible to use this offer in conjunction with the coupon code that was posted earlier on Ozbargain; will leave it to wiser people with personal experience of submitting coupons to discuss the possibility:
http://www.ozbargain.com.au/node/15385
EDIT:
best purchased with the updated coupon code (thanks to Pokitodki) and the RACV 15% discount code for your participating state (if you are member) bringing the final price down to $594.
thats the old model, isnt it?