It wouldn't be a deterrent for me. Health testing would definitely help the breeder immensely whether I bought a pet quality dog, or a show/breeding quality dog. They need to know what's in their lines. That being said, I would probably expect some sort of rebate just because it is extremely expensive. That's just me though. Most people I know have a problem paying what is asked for from most breeders for a dog, let alone having to pay extra for health testing, so it would definitely be a deterrent for them.

That being said, if you had an awesome family/person wanting a dog and they said no to the health clearances, I wouldn't let that turn you away from letting them have a puppy.