What happens when a price drops on, say, a hotel, an airfare or a rental car that you’ve already paid for? Here’s how you might recoup some money

Nobody wants to overpay for flights, hotels or rental cars, because saving money usually means you’ll have more avenues for enriching your travel experience.

Here are six sites that can help in your hunt for bargains. Knowing you’re protected makes it easier to commit to a flight, a room or a car rental.

Yapta.com and its iOS app (for iPhones and iPads) tracks flight prices on seven domestic airlines to help fliers get the best price before and even after purchasing their fare.

Yapta has saved fliers $750 million since 2007, said James Filsinger, chief executive.

After you enter your flight itinerary, Yapta will monitor prices and alert you if you are eligible for a refund or flight credit. Flight tracking is automatic when flights are booked using Yapta’s search engine.

Yapta’s customer service can assist if a traveler is uncertain about how to get a refund, Filsinger said.

For hotels, Tingo.com has proved to be “like found money� for George Hobica, founder of Airfarewatchdog.com, who uses it for personal travel. TripAdvisor launched it in 2012 to help travelers grab hotel deals.

Book under its “Price Drop� and Tingo will monitor your room rate for your trip dates. If the price decreases, the site automatically rebooks you at the lower rate and refunds the difference to your credit card.

Hobica cashed in on a trip to Las Vegas. “I got money back … on a two-night stay,� he said.

Although Tingo doesn’t charge a cancellation fee, some hotels do. When you book, the hotel’s cancellation policies are disclosed.

For those who want some backup for hotels, Booking.com, founded in 1997, has always used what it calls a best price guarantee, said Leslie Cafferty, vice president and head of communications.

“Hotels set the prices and you pay when you stay. You don’t pay in advance,� Cafferty said. If you find a lower rate at the same property in the same room category during your stay dates, Booking.com will match that lower rate.

For car rentals, AutoSlash.com tracks rental car coupons and rates in much the same way Yapta tracks flight prices. After booking a car rental on AutoSlash, the site checks to ensure you have the best rate. If a better rate is found with the same company, it will automatically rebook you at that rate. If the lower price is with another car rental company, AutoSlash asks your permission to rebook.

Priceline.com is the king of travel bidding sites. It lets travelers “name your own price� on a variety of travel products, but it doesn’t reveal the name of the provider until the bid is won.

It also has something called Express Deals that lets you skip the bidding process but still save money.

With either process, it offers a best price guarantee that “applies to every air, hotel, rental car, cruise and vacation packages sold on Priceline.com,� Flavie LeMarchand-Wood, Priceline’s vice president of communications, said by email.

“If you find a lower price for the same itinerary, we’ll refund 100% of the difference.

“Book an Express Deal and we’ll refund 200% of the difference.�

For Express Deals and Name Your Own Price, travelers can make a claim up to midnight the day before the trip begins.

Expedia also has what it calls a best price for flights, rental cars and packages. For this one, claims must be made within 24 hours of booking.

The new rate must be an “apples-to-apples comparison,� Tarran Street, head of technology public relations for Expedia, said by email.

For instance, you must be on the same airline, same cabin class (first, business, premium economy or coach/economy). The same holds true for hotels, ships and rental cars.

Trip dates and times of service must be the same as booked through Expedia. If you find a lower price, Expedia also will give you a $50 coupon to use.

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