The question isn't should you keep a store of duck fat in your fridge or freezer, but how to procure it in sufficient quantities? Pale golden, fragrant and deeply ducky, the cherished cooking medium of the Périgord and object of devotion for anyone who's ever rendered enough of the stuff to make confit is the king of fats. It simply makes everything it encounters taste better: pan-roasted root veggies, gurgling stews, fried potatoes, the creamy binding agent for duck rillettes and other potted meats. Frankly, it's good just spread on toast or eaten with a spoon.
Now to the eternal question of how to amass it in bulk: The easiest route is buying it already rendered, but it ain't cheap, especially in the volume you'll likely need to submerge duck legs for confit. Another other option is to buy whole ducks, separate the ample fat and gently render it in a pan with a little water over low heat. If there are poultry markets or Asian groceries near where you live, ask if they'll sell you just the fat and skin. It takes some hunting, but they're often happy to part with it for very little money. Once you've got it, keep it around: Unless you scald it, it's easy to save and reuse. Just reheat, strain and keep in the freezer, where it'll last up to a year and turns a beautiful yellow-white—that reminiscent of old-timer French vanilla ice cream.