
Just a tip, some of the best breeders don't bother advertising on the Kennel Club Puppy Register, prefering to take enquiries through their breed clubs and are likely to already ahve a waiting list.
The Kennel club will take adverts from anyoen with a KC litter, membership of a breed club usually means a deeper involvement in the breed,and I woudl always advise checking a breeder out through a breed club. the breed club will have a code of breedign ethics,a dn you can then check that the breeder breeds accoridng to it's priciples.
For shelties eye testing as puppies and later as adults for various eye problems would be a minimum requirement. These codes also set out best practice re age of homing and breeder responsibilites, so gives you soem reasurance when buying.