Less-expensive mice tend to have optical sensors, which offer good tracking sensitivity and tend to map well on a variety of surfaces, including textured ones such as cloth. Laser sensors, on the other hand, map onto the same or more kinds of surfaces (including some smooth or glossy ones that may give optical sensors fits), but they can be more finicky about rough surface textures. That said, we wouldn't let one kind or the other be the main reason you choose a mouse. Likewise, some vendors market branded versions of sensors that track, say, on glass or reflective surfaces. Don't take them too seriously, as you can solve any challenging mousing surface with...a $2 mousepad.
Dell Home, via its Member Purchase Program, offers its Dell 15.6" Laptop Gaming Backpack in Black/Red for $28.49 with free shipping. That's tied with our expired mention from four days ago as the lowest price we've seen for this bag. (It's the best deal we could find now by $20.) It accommodates laptops with up to 15.6" screens and features a shock-absorbent EVA molded front shield, adjustable shoulder straps, and a deployable rain cover.