An arpeggione is the offspring of a guitar, a cello, and a viola da gamba. It was first produced in the early 19th century, but aside from a Schubert composition, it never received much recognition until more recently when a revival in weird instruments reignited interest in the instrument.
It's essentially a cello with a fretted neck, six strings, and tuned like a guitar. It's meant to be bowed.
The only arpy I could find online that wasn't the price of a car was made by an outfit out of Hebei province in China called the Song Chung Musical Instrument Co.
Some modifications had to be made — replace the tuners, find the right strings, and under the care of the incredibly talented Scott Smith here in Seattle, the instrument received a new rosewood fingerboard, a crack that developed during shipping was fixed, and moveable frets were added.
The arpy gets used here as an overdub instrument to supplement synthetic strings and also as a "baritone upright bass." It's tuned like my Danelectro baritone guitar, as its body and scale as manufactured by the Song company is a copy of the famous cello "Sleeping Beauty."