I recently purchased a large set of SPC/KNT model sheets that were up for auction on Yahoo Japan. I've scanned the entire set and uploaded it here. They should be very useful for anyone who wants to attempt some fanart. Most of the material was already available on the web, but much of it is now in higher resolution than what was previously available. The filenames are KNT-based, so you might want to rename them if you're more familiar with the SPC names.

EDIT: Updated the link.
EDIT 12/21/14: Updated link again.