Check the listing for details. CTX-700 Portable Keyboard. Condition: Open box. Listed at 203.89 USD. The Casio CT-X700 Portable Keyboards' modest price makes it the right choice for casual or beginning players, and its stunning sound makes it a must-have for keyboardists of any level who need a portable instrument.What truly sets the CT-X700 apart from other portable keyboards is its heart: The powerful AiX Sound Source. This technology makes the CT-X700 sound like a keyboard costing hundreds, if not thousands of dollars more. Play a grand piano, and hear a meticulously-recorded 9-foot grand in a virtual concert hall.Play an electric piano, and hear vintage phasers and amplifier models that take you back in time. Play a flute, trumpet, or saxophone, and hear natural breath and vibrato.Play a bass, and hear the player switch techniques based on how hard you press the keys. Play a synth,.