I have yet to see real proof that airline companies get you to pay a higher fare by tracking your searches/browsing. While I'm sure you saw a $50 difference, it was likely a slightly different search, which is almost always what happens when people claim they've noticed this.
About a year ago, someone on reddit went out and offered a year of reddit gold for anyone that could, there was nobody: https://www.reddit.com/r/LifeProTips/comments/1ekv6e/lpt_bou...
As recently as last week, someone claimed they had reproduced, but they used slightly different search params and ended up with something totally different: http://www.reddit.com/r/travel/comments/2okml5/for_anyone_pl...
This myth is rife with anecdotal proof, but I've yet to see anything concrete.
I kept track of my searches in a spreadsheet, so I know for a fact that the price went up slightly (I think it was by 20€), and went back down immediately when I switched to a different browser.
Again, this was unfortunately too long ago for me to have reasonable proof, and it hasn't happened since (perhaps because I now tend to avoid Iberia anyway; they're pretty crappy in other ways as well).
Personally I don't search airline tickets outside of incognito , and preferably not without VPN or tor protection as well.
That price fluctuations are more due to activity than user profiling.
2. search it again.
3. the price has surged.
they don't track individual users, they track the search queries, this makes me wonder if flight search services are just rising the entire market prices, instead of a user only searching once, they constantly search the same query.
Not in general. The airlines account for that. (Otherwise, if the market could bear a higher price and still get reasonable demand, the airlines would have raised prices to that level in the first place.)
There are many sites that describe this happening, such as [1]. And I've seen it happen to me: a fare would go up by $50 while I was searching, and opening a private browsing window would make it go back down.
[1] http://www.halfwayanywhere.com/budget-travel/your-guide-to-c...