Why does the price keep changing after I click on a flight deal in Expedia?

What your noticing is a common practice known as dynamic pricing – And what dynamic pricing is, the ticket price can change depending on a couple of factors; 1. Number of people searching and 2. The timeframe they’re searching for.

So, by searching multiple times, you’ll see a higher price each time because now, more people have seen your search and decided to buy tickets at that rate.

A good rule of thumb, in order to avoid this, you’ll want to book your flights on the very first search you do OR use an incognito window, so airlines won’t be able to track your searches.

Hope this helps!

No one can be certain without access to Expedia’s logs, but it’s likely the lower price was previously available, but has sold out. The answer by @Mark Mayo gives a good summary of the general technology behind these sites. I’ve never worked for Expedia, but I have worked on similar systems.

For the specific behaviour you have seen, this could have been caused by Expedia getting their data from multiple sources.

1. A bulk source, that gives them prices and availability for thousands of flights at once. This will be imported to their database on a regular basis (e.g. once per day). This is sometimes called a flat file, although that refers to a specific type of technology and other bulk sources exist.
2. A live source, that looks at a single flight.

First all the flight data is loaded from the bulk source into the Expedia cache, which is then used to show you your initial search results. When you select a single flight, it goes and checks the live source to see if the price is the same. If there is a price difference, it displays the "Price change" message to the user and also updates the cache for this specific flight with the new live price. This is why if you run the search again immediately it will now show the higher price in the list of search results.

Some time later, they will run a fresh import from the bulk source. This data is now considered newer and more accurate than the live price retrieved for your individual search, and therefore the bulk price is added back to the cache.

In an ideal world, the bulk source has been updated, and it’s the higher price that ends up in the cache and the search results will correctly show the higher price and no "Price change" message. However, if the bulk source still has the lower price, then it will get added back to the cache and show up again in the search results. This could happen for a few reasons, including:

• The process to import the bulk data can be slow, especially as the data often needs to flow between multiple systems run by different companies. That price may have sold out between the start of importing the bulk data, and the end.
• The code that calculates the bulk and live prices is different. A bug in either can cause them to disagree about whether a flight can be sold at a particular price. e.g. maybe the $889 is a non-refundable fare but you’ve asked for refundable fares. A bug in the bulk import could have meant the $889 fare was classified as a refundable fare in the cache.

Expedia will have staff looking into these prices differences and working to fix whatever is causing them, but it’s a difficult problem to solve.

I run a flight search website (Beat That Flight) in Australia that aggregates sites like this. It’s one of the biggest problems.

Say you’re flying from Chicago to Los Angeles. There are literally thousands of possible routes (you might decide to fly via Albuquerque for some reason) and each route has multiple airlines, and times. All these flights often have different classes (Economy, business) and even within Economy, multiple pricing buckets.

All these are changing regularly, as people buy tickets, airlines price a lot based on demand, deals etc.

All this data needs to flow into various GDSs, across networks and have all the travel agency etc discounts added and updated. Constantly.

There’s a white paper here that explains in more detail.

From the whitepaper:

Just for San Francisco to Boston, arriving the same day, there are
close to 30,000 flight combinations, more flying from east to west
(because of the longer day) or if one considers neighboring airports.
Most of these paths are of length 2 or 3 (the ten or so 6-hour
non-stops don’t visually register on the chart to the right). For a
traveler willing to arrive the next day the number of possibilities
more than squares, to more than 1 billion one-way paths. And that’s
for two airports that are relatively close. Considering international
airport pairs where the shortest route may be 5 or 6 flights there may
be more than 10¹⁵ options within a small factor of the optimal

Short version – basically updating in real time is nearly impossible. Sites like expedia often cache prices, and update when there’s a search for a particular date/time, because there’s so many combinations there’s little value in say, updating El Calafate, Argentina to Dushanbe, Tajikistan in real time when you could be putting more resources into updating New York to Los Angeles – a more commonly searched route.

As a result, it’s not uncommon that the price you see has changed in the background. One of the tickets in a particular bucket may have just been snapped up elsewhere.

You can try, and indeed sometimes it’s a routing update that fluctuates and it may come back. But three days out, that’s less likely.

Hope that made sense.