"This week, we immediately saw an uptick of interest in our Internet e-commerce site, and this interest has continued and built immensely since his passing," Bruce Amster, director of sales for St. Croix Shops, said Friday.
The turtlenecks, made by Knitcraft, a high-end knitwear company based in Winona, Minn., sell for $175 at St. Croix Shops, the Saint Paul Pioneer Press reported.
On Friday, St. Croix Shops pledged to donate $20 to the American Cancer Society for every black techno-cotton mock turtleneck sold.
"Jobs understood the value of combining great design with advanced technology to create products of unparalleled quality," the store's Web site said. "At St. Croix, we share that vision and passion and commemorate his iconic look -- made in Minnesota."