I found this promotional offer which is applicable to in-store registration only. Register for mypost business account in-store and avail Band-3 discounts for 12 weeks. You can save 30% for the parcels destined to the same city.
Flyer reads as below:
Start saving with a MyPost Business account with Save upto 30% on same city metro deliveries on eligible parcels or upto 20% on eligible international parcel for first 12 weeks.
T&Cs:
Offer available on in-store registrations only until 30/Sep/2020. Band3 pricing is available for the first 12 weeks based on eligibility criteria. After the introduction period rates will be calculated on eligible parcel volume sent in a rolling 8-week period. Refer link below for eligibility criteria:
https://auspost.com.au/terms-conditions/send-and-save-terms-…
Despite what this say's it's not instore only.
My Aus post account has the same price since i created it (though im not sending that much yet) and i certainly didn't sign up in store.
https://i.imgur.com/AKoBFqB.png