Nebraska Furniture Mart offers the Microsoft Surface 3 10.8" 64GB Windows 10 Tablet, model no. 7G5-00015, for $398 with free shipping. That's a buck under our mention from December and the lowest total price we've seen. (It's also a current low by $25, excluding the mentions below.) It features an Intel Atom Z8700 1.6GHz quad-core processor, 10.8" 1920x1280 (1080p) multi-touch LCD, 2GB RAM, 64GB flash memory, 802.11ac wireless, Bluetooth 4.0, front and rear cameras, and Windows 10.
Several other merchants have it for a buck or two more including Best Buy, B&H Photo Video, Walmart and Microsoft Store.