Been looking for a U2415 and whilst not the cheapest ever, it's pretty good if you have the Amazon AU $20 voucher.
Amazon Voucher original deal: https://www.ozbargain.com.au/node/381343
Don't forget the 5% cashreward for Amazon (note that you need to submit a tax invoice due to issues with the tracking - refer to the CR website)
https://www.cashrewards.com.au/amazon-australia
Note: the cheapest non-cashreward, non-voucher vendors are the following:
$375 @ Umart
https://www.umart.com.au/DELL-U2415-24--UltraSharp-IPS-Monit…
$379 @ Mwave
https://www.mwave.com.au/product/dell-ultrasharp-u2415-24-fu…
How do you get the amazon $20 off voucher?