eBay
ATARI 520 STE + SM124 MONITOR.
2MEG MEMORY UPGRADE (MAKES IT EFFECTIVELY A 1040ST)
STEINBERG CUBEAT (V 2.0) WITH DONGLE
MOUSE
SOFTWARE (SEE PICS)
PEN MOUSE
2 X JOYSTICKS
CO-AX LEAD FOR TV
OWNER'S MANUAL
CUBEAT OWNER'S MANUAL

Bought in the 1990s for my home studio set-up, but hasn't been used since 2002. It's fully working and in very clean condition. 
(This version of Cubeat isn't the pre-Cubase program, but a fully-compatible lighter version of Cubase. As I recall, one of the things you couldn't do was draw note velocities etc but I may be wrong - it was a while ago. I recorded some sophisticated things with it and never thought that the software was letting me down).

Programs included are:

Cubeat
1st Word
Ani ST
Sim City
Robot Monsters
9 Lives
Final Fight
Operation Neptune
Paint ST
GFA Basic
C-Lab Explorer
Art Director
Canvas
Data Manager Pro
Vidi-ST
Band in a Box

Most of these programs came with the computer when I bought it and have never been tried.