On a spring afternoon, piles of unsold T-shirts sat on the floors of Mr. Tarrio’s headquarters in Miami, where he coordinates Proud Boys activities and runs the e-commerce operation. He said he had laid off some workers, office rent is harder to come by and legal fees loom. At a gun show in May, he said, he sat at a booth for hours and made barely enough in sales to cover the cost of the table... Mr. Tarrio of the Proud Boys found his businesses, including a merchandising site, booted by their credit- and debit-card processor. Later, PayPal also banned him, as did another payment processor, Stripe. Mr. Tarrio sought out new processors, including ones used by gun makers and porn sites, but said more than a dozen processors eventually banned him, and his bank shut his business account. After being shut off by one processor for what it called “hate propaganda” on a T-shirt that referred to a Democratic politician as a Communist and an idiot, Mr. Tarrio said, he had an idea: to launch a secretive e-commerce site to sell liberal merchandise with slogans such as Black Lives Matter and Impeach 45, referring to Mr. Trump.