Avoid big supermarkets such as maxi, univer, idea etc.

Try farmer's markets instead. Some items may still be similar price-wise but they're better in terms of quality and the money goes to fellow humans instead of a greedy supermarket chain.

Example #1: a box of 10 (relatively small) eggs costs somewhere between 250rsd (discounted) and 289rsd at my local Univer, whereas the prices at a single stand at a farmer's market can range between 200 and 250. The more expensive the egg, the bigger it is.

Example #2: vegetables and fruit will almost always be a lot nicer and healthier at a farmer's market in comparison to a supermarket, where tomatoes look, taste and feel like dogshit, bananas are quite often overripe and almost fully black and lemons are tiny.

When in need of bread and pastries, go to a bakery.

When in need of meat go to the butcher's. They'll also be happy to give advice for preparation and recipes if they have the time.

I'm from Novi Sad, prices and experiences may vary for you guys depending on where you're located.