The Square-1 is still being sold by Meffert's Puzzle and Games(MPG) at http://www.mefferts.com
Cost ~US$12 plus shipping worldwide, happy buying!!
Ebay has them occasionally for lower of course
I have to agree with u that this is one of the toughest sequential movement puzzles out there!
However, solution-wise is still memorize and solve thru experience, I even have a bandaged Square-1, it was naturally bandaged due to improper slicing of one moving plane, making it look as though u can turn the slice but in actual fact, it's bandaged within, so I formulated my own solution for that and now I feel pretty good about solving it in its complicated form.