People must desire them. They had probably been seen in some movie or with a celebrity, like a rock star. That's more likely to bring desire then if they were AKC ranked, which they wouldn't be, being a mix: despite Goldendoodles' and Labradoodles' popularity, they aren't in. Breeders will charge what people will pay. read more
For example, some "Lab" mixes have displayed the enthusiasm, trainability, and energy of a lab, while demonstrating the leaning, night barking, and double dew claws of a Great Pyrenees. I have met herding dog mixes where the dogs have behaved wholly like Great Pyrenees, they merely resemble their mix and have a bit more energy than a typical Pyr. read more
Adult Great Pyrenees need more exercise to keep them in shape, but not in hot or humid weather for fear of overheating. The proper amount of exercise can be difficult to regulate in giant breeds. Great Pyrenees are most satisfied when guarding livestock. read more