Amazon has the Sosoon 15.6" Laptop Backpack with USB Charging Port (FBA_LYSB01MT8DICR-OFFSUPPLIES) for $17 with free shipping for Prime members or on $25+. Has good Amazon Reviews.
Walmart has the Ozark Trail 30L Lightweight Hiking Backpack (TB2856-30L) for $18 with free in-store pickup or $5.99 shipping to home. List price: $37. It's made with lightweight nylon fabric and has a large U-shape zippered main compartment for easy packing and storage. It features a sternum strap and rain cover.
eBay has the 3-Piece Samsonite Centric Nest Hardside Spinner Luggage Set (multiple colors) for $200 with free shipping. Has good Amazon Reviews.