A secondhand vintage keyboard in good condition and working order.
Among Roland's line of early keyboard samplers—the S-series—the S-50 can be thought of as the professional model. Still, by today's standards it would be considered limited and lo-fi. However for its time it was a powerful instrument which can still prove useful for many music applications today. It offered a full 61 note keyboard with velocity and aftertouch sensitivity and 16 voice polyphony which was great for live and studio performances. It's easy to use, has an external CRT monitor support for large graphic editing and disk-loadable samples and operating systems.
The S-50 was used extensively in the late 80s by many top musicians of its period including Duran Duran and Vangelis. It was released with a less popular little brother called the S-10.