I know this post is a week too late, but I didn't want to post anything until I knew where fans of David's style could pick up his New York Fashion Week gear... I'm actually sad to say, I couldn't find any of his outfits except for his shoes and denim.... both of which are from Saint Laurent and I can confirm that his flat caps are not from Bates. I think the caps are from Lock and Hatters or Stetson but couldn't find the exact one.
UPDATE: After searching for a while I found the shirt he's wearing in the above picture, its by Saint Laurent!
I actually am in love with his suit and his whole outfit in general, it has a very vintage feel to it. If anyone out there knows where he picked up the caps or suit, please let us all know!