This worked at Burwood East, Victoria and something similar at Forest Hill, Victoria. I assume it applies to all.
1st Tuesday of the month is "Super Tuesday" discount day. Go Vita seems to crush their own peanuts and make some nice fresh (and very delicious) peanut butter.
This month, when I visited the Burwood East store, they were selling it by the 500g. I was a member (it's free to join; I think they just need your mobile number) and the 500g of crunchy peanut butter only cost $6.
It lasts a few months (not as long as Mayver's) but I prefer the texture, flavour (no added salt as far as I can tell) and price of this peanut butter.
There are Go Vita shops in all states (if not your town) so if it's convenient for you, you could check before next Tuesday if they'll have Super Tuesday and if they make their own peanut butter :)