The pic above shows Carl E. Walz playing a Yamaha PSR282 keyboard on the International Space Station. You can buy a PSR282 for about £45 on eBay, but getting a 11½lb keyboard into space would have cost NASA around $115,000.
The picture comes from NASA's Space Station Notes about playing music in space:
A lot of astronauts play instruments. There's even an astronaut rock-and-roll band. And a surprising variety of musical instruments have found their way into space: in addition to the keyboard, there's been a flute, a guitar, a saxophone, and an Australian aboriginal wind instrument known as a didgeridoo.