Dell is now matching the 52% discount they have on their single arm variant as posted by BatmanBeer for their dual arm mount.
Can also be stacked with 7% student coupon (no .edu email required so a throwaway is your best bet) (coupon claimed here) bringing the total down to $276.32
(I couldn't find the original Ozbargain Post for this deal)
Discounted Price: $297.12
7% Student Purchase Program Coupon: -$20.80
Total: $276.32 ( 55.36% off )
Delivery times look to be pretty bad unfortunately, my order is currently expected 30/6.
edit: instructions for 7% of coupon can be found in this post
edit 2: fixed coupon link
edit 3: Mine delivered today, shipping estimates seem to be super conservative as MonocleMoose had said.