The same applies to many other things in life. Basically don’t buy things unless they are necessary or add significant joy to your life. And if you do need to buy things see if you can find a second hand source, like leboncoin a vide grenier, a vide-dressing or similar. Its such a shame that freecycle hasn’t taken off in france.
Also look out for Trocs - books, garden stuff, clothes. Or swap things with friends.
But sometimes it’s better not to go for the lowest price and biggest saving… i have bought these products without really knowing how the idea started