The OzBargain favourite Dell S2721DGF has once again been discounted to what appears to be the lowest price on the Dell site since late September. 30% off as part of Dell's Boxing Day Sale, and an extra $39.15 off with the coupon code.
Both Shopback and Cashrewards currently have a 12% offer for Dell, which brings it down to $491.92 after cashback (do not use any code with this though). Credit to reilu in the comments.
Note: Estimated delivery time of 35 Days