Corian is the tradename for a Dupont product.
http://www.corian.com/
It is only sold through authorized Corian installers. (That I know of.) Usually these are kitchen countertop manufacturers. Almost every town has a couple.
There are other products like Corian but have different brand names. I can't think of them at the moment. If the kitchen countertop people don't use Corian they will mention the type that they sell.
Usually these guys have scraps available for sale to crafters.