Matchbox Robotech stuff is cheap. Generally why they may also be rare, there is less demand because a lot of the toys sucked. Battlepod prices went down when more people went for the cheaper Exo-squad versions instead.
I traded all my Exo-squad Robotech for MASK toys instead.
The Matchbox SDF1 is cool even though it's missing so many features of the Takatoku...but I think I paid $80 for my boxed one and I applied the stickers myself. I added an extra few as well to cover the holes at the top for the missile launcher which I thought looked stupid. The Daedalus and Prometheus are in sorry need for some detail though.
I would kill for a good sized DYRL SDF-1, not the small one released a while ago that claimed diecast but hardly had any metal and was uber expensive.