Walmart offers the Microsoft Surface Dock for Surface Pro 3, 4, or Book, model no. PD9-00003, for $124.99 with free shipping. (
For Prime members, Amazon charges the same.) That's tied with our mention from two weeks ago as the lowest total price we've seen. (It's also the best deal now by $24.) The dock acts as a charger and features two mini DisplayPorts, Gigabit Ethernet, four USB 3.0 ports, and audio jack.