Japanese Yamano offers a so called Hand Roll Piano with 61 keys.

The foldable piano connects directly to a computer to use it with MIDI software. The keyboard measures 102.5cm × 18.5cm × 2.8cm and weighs 1kg. The piano keyboard features a built-in speaker with output terminals for separate speakers or headphones.
After use, the piano keyboard can be stowed away in a pouch. Of course something like that has to come from Japan, where space is a luxury, but this foldable piano can have its values in a student dorm room as well.

Japanese Gadget exporter AudioCubes sells the Yamano Hand Roll Piano Keyboard for $279.00.