Bottle Feeding: Liquid, Powder or Ready-to-Serve Formula
Liquid formula concentrate: Easy to mix and easy to serve. Just mix the concentrate with water and you're a go. It's cheaper than the ready-to-serve stuff, but more spendy than powdered formula.
Powdered formula concentrate: The least expensive option, but the trickiest to prep for meal time. Powdered formula needs no refrigeration, but can clump and clog the nipple if it's not mixed well. Still, it stores and travels well and will give you the most bang for your bottle-feeding buck.