Red Devil, I saw a pair of Southern Cross rubber rain boots (child size, of course) on Yahoo Japan a while back, too. I have that coloring book, though, and as cool as it is, it really doesn't demonstrate that Southern Cross was some sort of a success. In fact, I think it does the contrary: just flip through the pages and you'll see the designs that never got animated or turned into model kits.
Yaco made a recent post about SC:
http://wildcats.pupui.jp/mt/archives/2006/08/post_100.html
I asked a friend to translate it and he said the jist of the post was that commercial aspects aside, Southern Cross was also a failure story-wise. He said that it had difficulty finding its audience and is pretty much forgotten nowadays.
My kingdom for a decent Bioroid toy, though...