The X100 series failed, in my view, as $500 "high end" netbooks: hot-running, clunky, and generally not up to Thinkpad snuff. Replacing Windows with Chrome OS and tailoring the system to its needs could be just the thing: the Lenovo X131e has a solid state drive, USB 3 and an ARM CPU. $430 for a machine with only 16GB of storage, though, is really pushing it.

Lenovo Thinkpad X131e Chromebook [google]