Listen, you cannot get a new leather briefcase for this cheap. It won't be real leather, and it'll fall apart. You're better off going with waxed canvas, or, better yet, go down the eBay rabbit hole.
Carl Friedrik Introduces Sonder Collection: Refined Leather Bags Designed for Modern Movement | stupidDOPE
The Sonder Collection is crafted from full-grain textured leather, soft to the touch yet built for the rigors of daily use. Each piece is designed to grow more beautiful with age.
The Perfect Margaret Howell Tote for Your Daily Needs
Margaret Howell's fashion philosophy emphasizes timeless, utilitarian design, focusing on creating reliable garments and accessories that age beautifully.