I also have a B/T bitch- and apparently she had a hernia- possibly the kind you refer to-which was not discovered until the breeder was petting her the other night whilst spending time with the new pup! They said it was nothing to worry about as it had almost certainly been there from birth, and was totally healed. Incidentally, Holly has given me no health issues whatsoever, is a beautiful example of the breed, and the breeders were disappointed that I'd had her spayed since they would have liked to have gotten a litter out of her. Maybe- since you appear to have fallen for this little bitch- you'd be better taking her as a pet, and learning the breed first hand? You could show her as suggested and learn the ropes that way, and leave breeding for a while until you've had more experience at assessing and looking at Cavaliers, as well as owning them. I might be way off base, but from your posts I get the impression that you've never owned a Cav before. Either way, good luck!
Incidentally, my little bitch had a bad start- her dam's owner got fed up with breeding and let nutrition suffer. Holy- along with her mother and aunt (I think) were to all intents rescued by the sire's owners when she was eight weeks. Apparently a few weeks earlier everything had been fine...The sire's owners worked with Holly to restore her health, and I paid full price for her when I got her at 12/13 weeks. I don't regret it. She may have had a bad start, but her lines are excellent.