You would have to breed a visual (actual) caramel to a 100% het pied. The babies would all be 100% het caramel and 50% possible het pied but they would all look like normals.

I try not to work with hets anymore so I'm not sure of prices unless I do some searching. A quick search of what they are going for on kingsnake.com would give you a rough estimate. Keep in mind that the top, well known breeders will always get a higher price because they can guarantee the genetics and often include picture ID .