I've heard that the little step platform (that fits over an individual stack of risers) is not available, that it was made especially for Cathe. I've also heard that someone has instructions for revamping a regular step platform into one of the minis.
Personally, I've never had any problem adapting the long platform, of course, I have extra risers which I got from fwonline.com - so I can get the height.
Jane