No secret, I was looking for corian on line using Craig's list and found this material listed as Corian sheets. They said it was used to cover bathroom walls in comerial bathrooms. The writing on the back was it some forigen language.
as I stated it carves very well ,I have some white in 1/4" and used it as litho, it is not as good as Corian. All my coaster and other carvings work very well.
you might do a search on craigslist in your area for whole sale corian sheets and find some too.