ALDI supermarkets are widely regarded as being cheap. http://www.aldi.com.au
The Discounted Gift Card wiki page contains a list of gift card portals that sell gift cards at a discount (or with cashback) everyday. These gift card portals require a membership to an organisation, ownership of a product, or are only available through employee rewards programs).
Retailers that have gift cards sold through these portals include:
5% off woolies gift cards for NSW seniors
Additionally, a small number of these gift card portals also sell prepaid gift cards that are restricted to merchants categorised as Grocery Stores, Supermarkets (amongst other merchant types). These are ideal when making purchases at independent supermarkets, greengrocers or health food stores that may not have their gift cards sold on gift card portals (e.g. ALDI, Supabarn, Foodworks, Drakes, the local Asian supermarket):
There are usually 10% discounts on IGA gift cards every few months.
Prezzee occasionally runs bonus gift card deals (or more rarely, discounts) on generic multi-retailer gift cards, which can be exchanged for Coles, Woolworths and
Check the current deals for the supermarkets. Coles Aldi Woolworths
Only buy the groceries that you need. Compare the prices in the catalogues if you have time.