How will the games be obtained on your end? Steam wallet funds?
He probably gets them from a country with redicilously low prices and then gifts them to another account (I mean: he has a guy in such country which sends him the stuff). Like EU region 2 is much cheaper in (most) cases than EU 1. EU 1 being like the UK/NL/Germany and EU 2 being Poland/Ukrain etc.
Russian prices are also a lot cheaper than EU or USA.
Be aware that if he is using this method Steam may find out and block the key as this is forbidden. There ain't a price difference for nothing, these people have less to spend. At least, most of them.