There is also an Australian sale for deals under $30 however options are limited, with exchange these may be cheaper so make sure to check both stores.
I got Black Ops III Zombies Chronicles $19.79US and GTAV: Premium Online Edition and Great White Shark Card $19.79US for a total of $60.52UD
US account required follow steps below for new account on - http://www.pushsquare.com/news/2018/12/guide_how_to_create_a…
Now as far as payment for games you will require either US credit card, US PayPal or US PSN credit, I used the below site for instant US PSN credit
https://www.g2a.com/playstation-network-gift-card-20-usd-psn… $20US for $30.26AUD
You can play the games on your regular Australian account as long as the US account is activated on your PS4 as a primary system
Just as a good example for US vs AUS store if you want F1 2019, it is $17.95AUD on Aus store or $17.99US($27.77AUD) on the US store. This is a very good example of the rare occurrence of a better deal for the Australian store.
Edit; Just found Assassins Creed Origins AUS - $17.95, or US$14.99($23.14AUD). Another good one not to buy on the US store.
Also, there are 367 total games on the US store vs 275 on the Aus store