I go to the supermarket once in awhile to buy stuff that I can’t really get for free.
Like salt, some butter, pasta, detergent, etc…

There is a big supermarket 3 train stations away from where I stay. Here, things are cheaper. It’s a big 2 storey supermarket. Something like Giant at tampines.

Then there’s another supermarket, which is considered the more atas supermarket chain in Paris. Probably something like Cold Storage. Selling some things which are better quality and some things which are the same but at a more expensive price…

I’ve bought stuff at both the supermarkets.
After some calculation, I realized that logically, I should be buying from the more expensive supermarket. 

Butter (President brand 250gm) at the cheaper supermarket is EUR2.10.
Butter at the more expensive supermarket is EUR2.19.

Both sell dried pasta that I use for under EUR1 per kilo.

The thing is… Firstly, I buy very little things. The price variation for the