A lot of times you don't need to buy containers, you can reuse the ones where your food came from.
For example inside my freezer there are three ice cream pots, but none of them has actual ice cream - it's tomato paste, chickpeas, cat food. In the past I've also reused margarine and requeijão pots to store leftover food, as makeshift planters, etc. The requeijão pots even worked as drinking glasses in my uni times.