If you can travel to TN, I believe that the University of TN does liver shunt surgery at a lower price than many. Something to think about.
Also, you could apply for Care Credit
CareCredit Healthcare Finance - Payment Plans and Financing for Cosmetic Surgery, Dental, Vision, Hearing, Veterinary & Other Medical Procedures to pay....but keep in mind that if you use that only some vets accept it. You definitely want a surgeon who is very familiar with LS surgery.
I would definitely beg, borrow and steal for one of mine. Your pup would have a chance at a long life if you get this repaired.