Why go through all that hassle when you can also simply buy CS:GO from a site such as G2A/Kinguin using bitcoin? You pay what, 1/2$ more than if you were to buy it on steam?
Really? Is your time spent dealing with all these sellers for 1-2$ really worth it?
It's because he didn't want to pay for anything at the first place I offered him 3 games in a bundle (CSGO, CSCZ, CSS) for only $10 If he kept his promise, the trade should finish sooner and cheaper than you buying anything on 3rd party platform.