Diplomats in Vienna are eligible for a tax refund on receipts totaling over 73 Euros. Check with your mission for details.
Some grocery and other stores in Austria have Kundenkartes (customer cards) that work in pretty much the same way as American store savings cards. Every week, certain items are advertised at a lower price for customers with the card. Cashiers will usually ask if you have the card when you check out.
Signing up for the cards can usually be done in the store, however, it may be easier to sign up online and have the card mailed to your local address. The sign-up forms are not complicated and you can always use Google Translate or ask a German-speaking friend for assistance. You can also sign up for email newsletters advertising special offers and sometimes including coupons.
Here are links to online forms for customer cards from several grocery stores.
These stores do not offer cards, but do have newsletters with special offers.
For other types of stores, Google the name of the store and “kundenkarte” to find online signup forms. Ikea, Baumax (hardware store), and many others offer these cards.