eBay has the adidas Iconic Premium Backpack (black) for $40 - 20% off in cart = $32 with free shipping. This backpack is made with suede-like material that looks luxe while being super durable. The sleek design includes an inner pocket for your laptop plus an outer pocket for stowing small essentials. Thick, cushy shoulder straps make the bag comfortable to carry.

Amazon has the AmazonBasics Premium Backpack (Black, NC1504159R1) for $10 with free shipping on $25+ or with Prime. Fits most 15" laptops, has 26.6 liters capacity, front pocket organizer, front carabiner clip, and external water-bottle pouches.

Has excellent Amazon Reviews.

Amazon has the adidas Unisex Hermosa II Mesh Backpack (Black, one size) for $20 with free shipping on $25+ or with Prime. Features 1 main zippered compartment with added organization pocket, side water bottle pockets, internal organization pockets, padded shoulder straps.

Has excellent Amazon Reviews.

Amazon has the Under Armour Loudon Backpack (679)/Mocha Rose) for $18 with free shipping on $25+ or with Prime. Has excellent Amazon Reviews.