The monitor's included, man... and 10 broken internal floppy drives... extra system boards... and 6 keyboards, 4 mice.
Says the floppy drives in the systems have all been changed out and work though.
It's nice to have a keyboard for some games, so I would hold on to those, and the mice.
Monitor, though, not really necessary since most regular PC monitors you can get outside Japan are compatible with the X68k video signal, as long as you have adapters for the different shape pin connector.