You can't buy anything thats overstocked or sell anything thats understocked on ironman. So this wouldn't work, thought I should let you know. If the shop isn't separate for ironmen, you could buy them upto the normal stock. Probably still not worth doing.
Tldr; Doesn't work.
Don't trade with this guy, he is very rude and disrespectful. Either he has never talked to a human before or something is fishy about the way he does things. Don't waste your time.