Nothing sells like success.

The president-elect is a source of fascination to Americans who can’t get enough of Donald Trump-related merchandise, according to one vendor.

Mort Berkowitz, who has been selling campaign buttons for more than 40 years, said he has sold out of Trump watches, and inaugural buttons are going as fast as he can make them.

Since targeting ads to new locales, he has been filling orders for Trump buttons from the heartland — including Minnesota, Iowa, Pennsylvania, Missouri, North Carolina, Texas and Oklahoma. Prior to the Trump phenomenon, Berkowitz said, most of his sales were from Democratic strongholds.

“Before the election, I sold as much Trump merchandise as Hillary Clinton merchandise. That’s never happened for a Republican before. Trump supporters are passionate,” Berkowitz said.

He displayed a wide array of inaugural buttons at his Midtown office, including one featuring Trump as Superman and the headline “Trump Triumphs.”