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 Incase Camera Sling Pack (Black, INCP300218-BLK) for $28 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.
Amazon has the adidas Originals Court Lite Sackpack (Purple Tint/ White) for $8 with free shipping on $25+ or with Prime. Has 6" shoulder drop, 100% polyester. Has excellent Amazon Reviews.
Amazon has the Travelon RFID Anti-Theft Crossbody Bucket Bag (42757 360) for $31 with free shipping. Features RFID blocking card and passport slots, locking main compartment, slash-resistant material, removable LED light, several pockets.