Check out this website for a certificate for savings.
www.friendsofanimals.org
I bought a certificate when I had my dog neutered last year and my current vet was a participating member. It saved me a TON of money.
Just look at the right hand side of the page under spay/neuter certifcates. Put in your email address and zipcode and they will email you a list right away of participating vets in your area.
I hope this helps.
Shelley