M-Audio Keystation 61es - $40 (charlottesville)

This is a well-loved usb midi keyboard that I'm not using anymore.
Sixty-one velocity sensitive, full size synth-action keys.
Minimalist but useful knobs and features.
Works flawlessly and is a great size for playing piano parts into a computer.
Comes with a decent 10ft usb cable, if you want it.