Kayak offers a flight tracker, a price alert notification service, an airline directory, baggage-fee directory and airport information.

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My favorite way to measure whether a market is overbought or oversold are Starc bands, as they can often alert us to price extremes.

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For airfare, register flight information on Yapta.com and you'll get an email alert if the price falls low enough for the carrier to refund the difference.

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It also allows them to specify the maximum price they are willing to pay so that users receive an alert when prices drop to a certain level.

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