M-Audio Keystation 49 - $49 (Columbia)

49 full-size velocity-sensitive keys with natural piano feel.
USB-MIDI connection for playing virtual instruments, controlling recording software, and more.
Transport and directional buttons let you operate your DAW from the keyboard, Pitch bend, modulation, and octave controls for expressive performances.
USB-powered and supports plug-and-play connectivity to your Mac or PC Lightweight design for easy setup and portability