eBay has the Targus City Laptop Backpack (TSB89004US) for $9.99 with free shipping. Compatible with most laptops with up to a 15.6" display. Features 2 water bottle and front zippered pockets, shoulder carrying straps, top carry handle, reflective elements.
Amazon has the Under Armour Adult Loudon Backpack (Baroque Green (311)/Black) for $20 with free shipping on $25+ or with Prime. List price: $40. Features 100% polyester, machine-washable, soft-lined laptop sleeve holds up to 15" MacBook Pro or similarly sized laptop.
Has excellent Amazon Reviews.
Amazon has the Incase Camera Sling Pack (Black, INCP300218-BLK) for $26 free shipping. Constructed from premium, durable materials stand up to the conditions of every degree. Suitable for DJI Mavic Pro or similar size drones, medium to smaller body DSLRs and action cameras.
Has good Amazon Reviews.