For packaged goods, dairy, water, and household essentials, your absolute cheapest options are Turkey's national discount chains. They are stripped-back, no-frills stores that focus heavily on high-quality private label items over global brands.
BİM: Usually considered the absolute lowest baseline for prices. It is the best place to stock up on basic dairy (like yoğurt and peynir), bottled water, olive oil, and basic pantry staples.
A101: Highly comparable to BİM but tends to carry a slightly wider variety of name brands alongside their budget house brands. They are also famous for random weekly non-food deals (textiles, small electronics).
Şok: Very similar pricing structure to BİM and A101, but they frequently have slightly better fresh fruit and vegetable sections than the other two discounters.
Crucial Note: BİM, A101, and Şok do not sell alcohol or tobacco items due to corporate policies and licensing.
If you are looking for beer or wine, you will need to head to Migros or a local Tekel Bayii (corner shop).