Wow, there are now some tall tales going on on this thread!
The breeder's unscrupulous, the dog has major behavior problems, the couple isn't just older with health problems, they're
elderly, dog's a handful since it needs training classes, runt of the litter, won't come back when called, missed two crucial years of training, etc.
Good grief!
Look, OP, take everything that everyone says here, including me, with a grain of salt. Go meet the dog. Talk to the people. Bargain with them. Read the original contract. Walk away if it doesn't feel right or if you can't get the price you think is fair.
The dog likely came from a decent breeder. That breeder planned for her birth, oversaw it with one of her own beloved dogs, and nurtured the puppy for the eight weeks or more that she was with her. She sold the pup to people she believed would take good care of the dog, and by your account, they have. They may well have been repeat customers or customers of another breeder known to the breeder of this dog. They loved and cared for the dog, and perhaps it became a lot. That can happen. Many of us are guilty of this when we take on a puppy, dog or other pet. (I remember the feeling myself when I got a puppy while still undergoing chemo.) Life happened for them, and someone is now having health problems. They feel the dog would be better off in another home and they're trying to find the right home for the dog now. Another loving home, like the ones she's had already. She does not sound like a ruined dog; she sounds like a well-bred, young one just out of puppyhood and still a year away from maturity. Hardly a lost case.
This is much different than a dog who's been abused or neglected or has unknown heritage or major behavior problems.
This dog has had a very good life so far. It is highly unlikely that there are major problems with the dog. I have a dog like this now who got an incredibly great start in life with a good breeder, then came home with us. I know his siblings and relatives and all of them are pretty well adjusted - in large part because of their great start in life and the people chosen to raise them. My sense is that the dog will be a good member of your family with some fine tuning of his training and socialization. You know this if you have experience with the breed. Herding dogs need structure, consistency and firm leadership. Fences are often required because they are protective of the home and their intelligence and instincts will lead them astray. The last thing anyone wants is for the dog to wander out into traffic and get killed. Requiring a fenced yard doesn't equate to either behavior problems or to leaving the dog outside alone to languish all day - since they are barkers the neighbors would be all over that. We have a fenced yard and our dog can explore on his own while pottying, go in the pool with us, play fetch, have doggy friends over to play, hang out with us when we're working out there and such, yet he's safe there both from predators and from leaving this safe space when his nose sniffs out pesky critters. Some dogs are prone to running off and for many it's instinctual.
OP you aren't just doing them a favor, you were looking for a dog from a breeder and I'm sure didn't expect to get one for free. If you did, you could've scoured Craigslist or gone to the local shelter. You sought out a dog from a known breeder for a reason. Stick with your gut sense. We don't live in an area where much comes at a cheap cost. As I mentioned, I've been looking for a rescue and some of the costs have been what I thought were very high, too, as much as $800 and requiring a trip out of state to get the dog without even meeting her. I think the price of the dog seems high with the other requirements, but probably not high without them. YMMV.