

When a US city's airport is controlled by a single airline, that city becomes disproportionately expensive to fly into — the airline has no competition. But you can often get a bargain by booking a ticket that has a layover in that city and then abandoning the second leg of your trip. For example, to fly from Des Moines to Dallas costs $375; flying Des Moines to LA via Dallas costs $186 — all you need to do is get off the plane in Dallas with your carryon-only bag. Airlines' terms of service prohibit this, but their only remedy if you get caught is to bar you from flying with them anymore.

1. Look to employ the switcheroo when your final destination is at a hub airport dominated by just one or two carriers, like Atlanta, Cleveland, Salt Lake City, Charlotte, Detroit, Cincinnati or Chicago O'Hare, all of which have overpriced tickets.

2. When you're traveling to one of those cities, you should search for phantom flights into airports that are more competitive — New York, Miami, Las Vegas and Boston are good examples. Search engines like Kayak.com will allow you to select your routing through your desired layover airport.

3. Book your itinerary as a set of two one-way flights, rather than as a round trip. If you miss any segment of your itinerary, the airline will usually cancel the rest of it.