For videotape and laserdisc releases in Japan, your best bet is to have a friend over there that can search for you. Used LD and VHS don't show up as much online.
If you're planning on ripping the Japanese tapes for Mighty Orbots, I'd love to see that completed. There's a complete set of episodes on the spleen that look really good compared to other sources I've found but your screen cap looks like it might be even better.