To find a Board Certified Orthopedic Specialist go to:
American College of Veterinary Surgeons
You can apply for Care Credit at:
CareCredit Healthcare Finance - Payment Plans and Financing for Cosmetic Surgery, Dental, Vision, Hearing, Veterinary & Other Medical Procedures Most surgeons accept Care Credit and the payment plans are usually reasonable in terms of interest rate.
The surgery is not cheap if done by a specialist, but in the long run your pup will be fixed! I have seen many people let general vets do this surgery and end up spending more in the long run because it fails.
Here are some links about luxating patella that may be of help :
ACVS - Health Conditions Yorkie Haven Rescue - Patellar Luxation Info