Cost do vary from State to State.
What makes you think he has a liver shunt? Has you been to a Vet, actually a Specialist in Liver Shunt Surgery?
I don't know where you are located, but U. of Tenn is probably the BEST place to have liver shunt surgery performed.
The University of Tennessee College of Veterinary Medicine - Liver Shunt Research
Dr. Karen Tobias:
UT College of Veterinary Medicine Faculty -- Karen M. Tobias