I’ve learned to instead allocate $50–200 per trip to a “settling fund,” which I use to buy needed items once they’re 100% needed. This includes cumbersome and hassle items like umbrellas and bottles of sunscreen that love to explode. Also, never buy if you can borrow. If you’re going on a bird-watching trip in Costa Rica, you don’t need to bring binoculars—someone else will have them.
