We've compiled a list of Judaica shops in New York and New Jersey that sell challah covers. About a dozen are currently marked "Temporarily Closed," presumably due to COVID-19 limitations.
All of the Judaica superstores are located in Brooklyn, with almost a half-dozen smaller Judaica shops in Lakewood.
Judaica World
329 Kingston Avenue, Brooklyn, NY
A dozen faux leather challah covers priced at $175 to $300
The Judaica Place
1917 AVE M (Between east 19th and Ocean Ave) in Flatbush
Large selection priced between $18 and $290, made by Galilee Silk, Alexander Gallery, Karshi, Yair Emanuel and Majestic Giftware, Ronit Gur, Waterdale Collection

Mekor Judaica
1973 Coney Island Ave. Brooklyn, NY
Prices range from $45 to $180
Eichler’s
5004 13th Ave, Brooklyn NY
A selection of some two dozen faux leather and white brocade challah cover made by Waterdale, Art Judaica, A&M, Mefoar, Malchus, Legacy Judaica and Majestic Giftware, ranging in price from $30 to $300
Greenfield Judaica
1366 39th Street Brooklyn, NY
Brocade, cotton, leather, terylene, satin, organza, velvet, silk, suede and vinyl from under $20 to over $300
Another half-dozen Judaica shops in Passaic, Teaneck, West Orange and Lakewood. A notable challah cover maker in Lakewood is the Waterdale Collection, which features PU leather challah covers.
If you'd prefer to shop online...