[2021] Any legal way to buy a factorio key with steam prices, but not on steam? (more in thread)

By legal I mean a way that will make money go towards Wube, and not a gray market reseller.

I'm intending to buy factorio for my brother in law as a birthday gift, but he doesn't have a steam account so my plan was to get a key from him and then gift him an envelope with the key and instructions on how to use steam.

To explain, I'm in Poland and factorio on steam costs 70 PLN, (really good price btw) but you can no longer do the thing where you buy a gift and then gift it to someone else later. So I checked on the website and there it costs 25,40 euro or about 116PLN. Worst comes to worst I'll buy it there but I was wondering if any of you have a recommendation on a place to buy it at about the regional price for me ,cause I'm cheap.