This is called Regional Pricing. Some developers, and steam, acknowledge the hardships around the world and how its worse in some countries vs others. So pricing is adjusted to fit their countries economy. 80-90% of game keys sold via a third party are from Turkey, Argentina, Russia, etc. (Assuming they aren't true sellers who have developers with published games or connections to devs with tons of games to get keys directly from the source.)
One of the guys above is just promoting his own site reselling keys. No other reason to point people to a website then continue to insist they offer the "best service".
The problem is you cant just change region to turkey, you need a proper proxy and nowadays if you plan to get away with a lot of buying, you need a Turkish number, Turkish debit card (to fund the steam account in Lira and not USD to be able to pay), and then you can buy games for cheaper.
Second problem, switching region of your account back. Once/if done, if any of those games were like free and you bought stuff in them, they can now see you used turkey to pay cheaper and changed after and can ban you. (I can prove this happening with at least Warframe as an example.) They can see which country sales originate from, don't abuse it without proper opsec.
With new forums people are quick to post useless information without going deeper into it or posting knowledge. Just, "hey you can do this, youre welcome, bye" Or
You can buy super cheap games from turkey websites aswell
Who posted 50% of the same info the FIRST post says.