A complete Windows tablet/ultrabook does exist around that price point - I got a refurbished Samsung Galaxy TabPro S Gold for $525 shipped last August. It's got

A complete Windows tablet/ultrabook does exist around that price point - I got a refurbished Samsung Galaxy TabPro S Gold for $525 shipped last August. It's got 8GB of RAM and a 256GB SSD, the only real thing that differentiated it from the more expensive devices out there is the 0.9Ghz m3 CPU. It included the keyboard cover. FWIW, I haven't used it since I bought a 6th-gen iPad with LTE. It suits that role better for me.