Amazon has the AmazonBasics Slim Carry On Travel Backpack (Overnight, Salmon) for $18 with free shipping for Prime members or on $25+. Has good Amazon Reviews.
Ends 8/10. Amazon has the Sunhiker Small Hiking Backpack (Several Colors, M0714) for $30 - $15 off with coupon 50C68OUK = $15 with free shipping. Features 20- to 25-liter capacity, side bottle holders, water-resistant.
Has good Amazon Reviews.
Amazon has the Osprey Porter 30 Travel Backpack (Black or Castle Grey) for $72 with free shipping. Has excellent Amazon Reviews.