Best Buy offers the Microsoft Surface Dock for Surface Pro 3, 4, or Book, model no. PD9-00003, for $99.99 with free shipping. That's $25 under our mention from Black Friday week and the lowest total price we've seen. (It's also the best deal now by $26.) The dock acts as a charger and features two mini DisplayPorts, Gigabit Ethernet, four USB 3.0 ports, and audio jack.