Got this in a promotional email just now, seems like a good deal. Appears to include all colours, which is a bonus.
There's a link to a $5US coupon on the item page, just click to redeem it, then select it during checkout.
After adding GST it comes to $455.40USD. (sorry, I had the wrong conversion originally in the title)
Of course the OnePlus 6T has just come out, but I think this is still a great price for a great phone.
As a note, the site considers the order "done" as soon as you get to the payment stage… which is I think the first time you see the GST added. Thankfully you can just cancel the orders with one click on your orders page.
EDIT: a $20 discount may be possible with code ONEPLUS02, see here
Wow great price for a great phone.