Buy in bulk

Buy non-perishable goods in bulk: paper towels, toilet paper, deodorant, razors, shampoo, mouthwash, pens, paper, tape, staples, candles, energy bars, dog food, printer cartridges, t-shirts, underwear, motor oil, housecleaning supplies. Unless you are financially limited, moving, or expecting to die soon, there is no reason not to have a 1-2 year supply on hand.

Buying in bulk is rational because the value of your time exceeds the time value of money in petty amounts. In other words, whatever opportunity cost you incur tying up capital in bulk goods is outweighed by the value of time saved not driving to the store for a year.