Are russians pay their CSGO crate keys less expansive than other countries ?

Just Russia Things.

Other people get them from trades and sell them to him for even lower than what he sells them for, people who trade in keys need to exchange them for money at some point, and that's what he does, he is a key reseller.

i would guess they buy it in masses from farmers and such, otherwise that kind of pricing is purely impossible (then again the currency difference may come into play too). This or the keys are dodgy

Just converting steam wallet to Paypay, that's how you do it.