A single piece of food-grade silicone that catches let-down milk while you nurse on the other side, for the price of a takeout lunch.
The Haakaa isn't really a pump; it suctions to your breast and passively collects the milk you'd otherwise lose to a nursing pad, which adds up fast in the early weeks. It's cheap, dishwasher-safe, and has no parts to lose or replace, which makes it a near-universal recommendation. The suction base can tip if you're moving around, and it won't build a big freezer stash on its own. Skip it only if you're not nursing at all, since it relies on natural let-down rather than active suction.