What a nonsensical argument. Deodorant is a consumable good. In scenarios like this, 40$ for 4 == 10$ for 1, because you consume it at a steady rate, and what you don't buy now you will pay for later
Do you live in a microhome? Deodorant sticks are tiny, surely you can store 3 of them under your sink for months without too much suffering.
Never noticed any problems with them.
Mine is 2 years