[ I personally have to admit I've bought some items myself, but I want to redeem myself for breaking that rule. I hope that this will have no further consequences for me myself, if it does, I guess it's deserved.]
I do not have direct proof, but he does have a link to a DD RL-Trading site in his link, wich could be indirect proof to research it. It shouldn't take long to confirm that he indeed, sells for USD.
EDIT : His alternate account : http://steamcommunity.com/profiles/76561198054587960