I know that those flight ticket companies use a tons of cookies and raise the prices after few searches.
Some do, but as with everything, you should be removing cookies before you purchase when possible too.
(Not gonna go into it as it's a banned topic here)
I read somewhere that the price depend too of the day when you are buying it ( tuesday night should be cheaper than sunday during the day ).
Also yes, but that would depend, on the flight, where it's going, your seat class & also it's fillable rate.
For example, USA domestic flights will tend to be cheap the moment it's available, and price will go as it creeps closer to it's departure.
I know earlier this year, i got my LA to MIA ticket for $200~ (I got it reserved it months in advanced). About 12 hr before departure, it was being sold for $500
A few hrs prior to departure, I got a msg from AA saying, someone would buy my ticket for $900+. Would I want to sell it.
At the same time, if a flight going overseas (especially in these COVID times) is not filled up. The price will drop until it has a decent fillable rate, if they still can't reach a certain %, depends on the airline but they may just cancel the flight itself.
Do you guys know if they are countries cheaper than other when buying flights? With low rate taxes etc ?
Yes, some countries can actually get flights cheaper, but there are also hurdles you may have to across to get those pricings.
For example, some may ask for ID & some may want you to pay by a card of that country.
Also, not all countries will offer flights from X to Y also.
For me personally, I have studied tourism & I have quite a few travel agent friends, I always just have them book the tickets are the best rate possible for me.
You can take a read at this for example (Providing also a Cache version as it's actually a "Paid Article")
Cache:
https://webcache.googleusercontent....-that-enjoy-the-cheapest-flights/+&cd=8&hl=en
Non: Cache:
https://www.telegraph.co.uk/travel/news/the-nationalities-that-enjoy-the-cheapest-flights/
