This is a very hard one. Deciding to own a dog is a very personal decision.
How many people on here could honestly say that if they didn't have a Cavalier, they would choose a "mutt" from rescue instead? I know we would not. If I couldn't have a Cavalier, I don't think we we would have a dog at all.
I guess all we can do is what is right for us - my answer to people who criticise the money we spend on the dogs, saying that it could be better used elsewhere, is to ask if they are prepared to give up their holiday/tv/stereo etc {whatever THEY choose to spend their money on} to donate instead.
I have had rescue Cavaliers in the past, also retired show/breeding dogs. I have also fostered for rescue, and continue to fund raise for rescue, and to help and support health and welfare projects. This is my way of helping those not as fortunate.
Cavaliers fit in with our lifestyle, we adore their temperaments and everything about them, other than the heartbreak of dealing with health issues
We all need to be going to health focused breeders, and supporting them, and encouraging others to do likewise, thereby eventually forcing the bad breeders out of business.