As for me, my method cost just $13, and it’s probably saved me $300 on carry-on baggage fees in the first year alone. My sister first introduced me to the Caremore Duffel Bag. (To buy: $13; amazon.com.) In a Mary Poppins–esque flourish, she arrived for a weeklong visit with nothing but a small duffle bag—and managed to bring a pair of jeans, a few pairs of shorts, and several tops (plus about a dozen small Christmas gifts) with her. amazon.com I was sold. The bag is a game-changer when it comes to flying on a budget airline, where a typical carry-on bag—say, a duffle or wheeled bag you’d stick in an overhead bin on a traditional airline for no extra cost—can come with a fee of more than $40. This economic bag is specifically designed to suit the required personal item dimensions for Spirit Airlines carry-on bags, so I can carry it on as my fee-free permitted item and still bring everything I need with me. (At this compact size, the bag will likely also fit carry-on requirements for United Airlines, American Airlines, Jetblue, and more—just be sure to follow carry-on luggage rules.) The only real difference between this personal item and a traditional carry-on is that, rather than throwing it in overhead storage, it fits at my feet, under the seat in front of me—for free. That’s no small thing for anyone traveling on a budget. This bag may not seem like a particularly great hack until you consider how much it can hold. At 17.7” x 13.8” x 5.9”, the bag sounds small, but looks can be deceiving. The bag easily folds up small—so storing it while you’re at home is easy—but it opens into a nice rectangular duffle with two expandable carrying straps and an attached side pouch. I can typically fit four or five outfits into it when each top and bottoms are rolled, usually with room for an extra pair of shoes, a toiletry bag, and my flatiron. (Priorities, you know.) Knowing how to pack a carry-on helps me fit everything in. If you’re a really talented packer, you can also stash a book for the flight and any other small item you might need—but it’s a good thing cute luggage tags don’t have to fit inside the bag. When I used this suitcase for the first time, I was surprised and relieved when my bag fit easily into the carry-on bag size-checker, even when it seemed to be bursting at the seams. Now here’s the catch: Policies for most budget airlines treat your personal item as your one free item, so you’ll want to make sure you can squeeze your purse into the bag, as well, at least until you’re on the plane. That’s usually when I separate my items to store them side by side under the seat. Downsizing your purse is an option, as is forgoing one altogether. Another downside to this bag is actually carrying it. The bag is made of waterproof, tear-resistant Nylon, which means it’s super lightweight—just about 10 ounces when empty. But once you pack the thing full, the straps sometimes dig into your shoulder with the weight. Buying a padded strap insert works as a solution, as does carrying the bag by hand or packing lighter. But for those quick weekend trips, this bag saves money, time, and space; plus, it ensures that my luggage won’t get lost on a connecting flight, possibly ruining a brief trip. When I bought the bag, color options were limited. Now, you can choose from about a dozen shades. And while I bought mine specifically for Spirit, I’ve used it on Frontier and JetBlue, as well. Many reviewers have said that while the sizing sounds oddly specific, it works for many airlines and plane sizes. For just $13, I’ve stopped having to pay that $30 to $50 fee per flight for a large carry-on bag. Considering the hassles that come with overpacking, I think I’ve saved myself a few headaches, too.