The
Samsung ATIV 500T is a top-level Ultratablet (removable keyboard like an ASUS Transformer), on sale ATM for $619 w/ keyboard at MemEx. They have 1 left on the online store, be quick!
NCIX has it on for $600 even, but I don't think it comes with the keyboard.
EDIT: I'm an idiot. The keyboard is $150 extra.
The
Asus VivoBook X202E is on for $550 and is a full touchscreen Ultrabook.