This situation sucks
...
At 9 months old, he can still live a long, happy life. If he were older or the prognosis dire, then it would be a less difficult decision.
I would definitely be all over the breeder ... as in calling every day. Re-read the contract if you have one, most have a health guarantee for the first year.
Liver shunt is often treatable.
Hip dysplasia is treatable.
The cost is what is so hard to fight with. It's tough because we don't want to back down if it is something that we could have helped with. At the same time, at some point the $ becomes too great of a factor.
Sending good vibes ...