I would have to agree with the others, as far as affection goes. My husband and I just got a Sheltie puppy, Lerwick, in August. He's 18 weeks old now, and is teething, and still very much in the stage where he wants to play all the time, and isn't often in the mood for petting or cuddling (except when he is very sleepy). I don't think he will be overly snuggly when he is an adult either... I think he'll always want to be around us, but not constantly wanting cuddles.
My family had a Sheltie when I was a kid, Specs, and she was affectionate, and always willing to be petted and snuggled, but wouldn't necessarily come bugging you for it, either. She would, however, sit on your feet whenever she could. Specs also had a lot of health issues, very similar to yours, it sounds like. She had a bad hip from quite an early age, was about twice the size a Sheltie is supposed to be, she had kidney failure, she went blind. My parents bought her from the breeder who lived in town, and didn't pay much for her. When they took Specs to the vet for her first exam, he checked the dog over, and then asked Mom how much she'd paid for the dog. She told him (she actually told him she paid $50 more than she really had), and he said, "well, you get what you pay for."
So, I totally understand your fears about Sheltie health issues. When my hubby and I decided we wanted a Sheltie, I became almost obsessive about finding a breeder I felt I could trust, because as much as my family all loved Specs, I didn't want to go through what my parents did because of her genetic shortcomings. This was also what made us decide against adopting a Sheltie from our local Sheltie rescue. Besides the fact that we would not have been allowed to adopt because we don't have a fenced-in yard, we were also concerned that as first-time dog owners, we would not be up to the challenge of properly caring for a rescue Sheltie's unique psychological and physical needs (all the ones at our rescue are special needs... I have never seen one listed on their site that wasn't). For us, the best option was to buy a healthy puppy from a reputable breeder. It's finding that reputable breeder that is the challenge, of course.
At the bare minimum, a reputable breeder will offer genetic guarantees against health defects (the breeder my parents bought Specs from offered no such thing, of course). I decided that for my peace of mind, I would contact my local American Shetland Sheepdog Association breeder referral chairperson. I felt I could trust the ASSA to appoint truly knowledgeable people to that position, and that they would, in turn, only recommend truly worthy breeders. Our local contact was extremely helpful, not only in answering any questions we had about the breed, but also in helping match us with a breeder. The breeder we eventually went with is one she works with often.
Looking at the ASSA website, it looks like they've updated the site to actually list breeders, instead of just a referral contact.
http://www.assa.org/breeders.html There is also a great section on how to buy a puppy
http://www.assa.org/buy.html that has links to a list of questions to think about and ask a breeder. This is definitely where I'd start my search.
