I heard that Airlines do not like you shopping around for prices from someone who did this research. They log you when you first come on their site. If you come back 2-3 days later, they will jack up the price, presumably to scare you into buying tickets.

Yes, I heard the same story from these friends as they were telling me this.

One of them works for a travel agency.

What's the best work-around to avoid this price jack?

clearing cookies, or just using incognito mode in whichever browser you are using usually does it. They've been doing this for at least a decade now, IIRC.

I'm surprised it's legal. Didn't Amazon have to backtrack on something like this?

They did backtrack, but because of PR reasons, not legal ones. Unless there are antitrust issues, it's perfectly legal to offer different prices to different customers.

Semi-related fun fact: at least on American Airlines' Gogo service, in-flight wifi requires you to pay for each device separately and charges more for laptops than for mobile devices; but it just checks your MAC address and user agent, respectively. Have your laptop browser identify as a mobile to get the better price, or buy on your phone/tablet and then spoof its MAC address on your desktop to use both devices for the price of one.

This is total B.S.

When you do a search on a travel website (including most airlines official sites) you are actually being served results from a GDS. These companies (Worldspan, Sabre, etc) pull in airline/hotel/etc availability and produce an a search and fulfillment API. They are the reason you can get a flight that connects across multiple different carriers.

I've built a number of successful OTAs (Online Travel Agencies, aka websites) and never once been asked to provide visitor IP addresses or cookies.

In the early days of the internet doing repeated searches would increase prices because these systems were designed for travel agents to do a small number of searches, and a spike in searches was a demand signal. Almost all demand based pricing has been eliminated from air and hotel because of internet "casual shoppers" and price wars.

Well it's true. I've had it happen to me multiple times. Do a search and find a flight at price X. Clear your cookies and repeat search (maybe on another day?). The same flight will show up for a lower price.

Do a google search for "clear your cookies before booking flights" and you can read all about it.

If you're doing it on another day, the inventory (and thus price) probably changed. The price of a seat on a plane is dependent on how many other seats have been sold.

Sorry, my wording was confusing. I'm saying that on another day if you repeat your search you might get a higher price. Then, clear your cookies and search again- boom, back to the lower price. I've seen it happen 3 or 4 times now.