I'm interested in how much Trump apparel is out there: how much has been produced or ordered or sold by his campaign, how much his supporters have bought or been given—and how this compares to that of other presidents.
By Trump apparel, I mean clothing or accessories that support Trump's political career, both his election and his presidency. The most notable example is probably "Make America Great Again" hats.
I'm most interested in apparel distributed by Trump or organizations led by him, but if there's a significant amount of apparel that's distributed by his supporters or other individuals or groups not directly tied to him, I'm happy to consider that too.
Information around this topic seems limited. Here, in June 2016, the Washington Post says Trump's campaign had spent more than $2 million on hats. Here, TMJ4, an NBC affiliate, says that "two months before Election Day," Trump's campaign had spent $3.2 million on hats.
Neither of these sources makes it easy to figure out where these figures are coming from. (WaPo says "campaign finance filings"; I can't figure out how they get that from the filings on the FEC's website.) Neither considers apparel beside hats. And neither considers how this kind of spending compares to that of other presidents.