Amiga mice can sometimes be difficult to be find. They are direct-switch and don't use any sort of protocol like PS/2/USB/ADB mice do. However, many ancient DOS machines used the Logitech Bus/Microsoft InPort standard, which is electrically identical to what the Amiga used. Only the pinout is different.
|Signal||Amiga Pin||Logitech Bus Mouse Pin|
|Left Mouse Button||6||6|
|Middle Mouse Button||5||7|
|Right Mouse Button||9||8|
Logitech Bus Mouse connector: