It is really hard to find a good breeder out there, especially with the internet. Take your time to sift through the websites and ask lots of questions. You get to compare many different outlooks on the breed that breeders have. You need to match yours with thiers. I am not going to say that certain breeders are better than others because it really depends on what you are looking for. There are some very unethical breeders though. You don't have to pay $3000 for a puppy if you are looking for a pet. Please be aware that sometimes a higher price doesn't mean that the puppy will be a better dog. But lower prices MIGHT mean you are looking at a puppy mill or someone with unhealthy puppies. In general a good breeder can be almost anybody as long as they are well informed, continually learning, breeding for improvement, willing to offer a health guarantee and wants to take puppies back in the event you can't keep them. When I look for a puppy I tend to stay away from breeders that:
Have many litters per year (there is no way that all their puppies are getting the highest of care)
Have many dogs (Again there is no way you can pay enough attention to many dogs, be careful here as many dogs are co-owned)
Breed their bitches before 2 years of age (Although accidents happen, Great Danes should not be bred before 2 years preferably later. If they are breeding before that you might question thier ethics)
Breed thier dogs more than once a year (This really is hard on the dogs and shouldn't be done, again you should question why they are breeding dogs)
Say they have a "rare color" (While some colors are harder to find, I wouldn't consider any "rare". Usually this means that they have bred dogs outside of the color guidelines .
Breeders that are selling or giving away older dogs (Again I believe there are exceptions to this as life changing events do happen. My thought is if these dogs are part of thier family, why are they willing to part with them?)
I was thinking of these things while looking through tons of websites and thought I would pass along my thoughts. I really don't think there is a perfect breeder out there just better ones. Each breeder is striving for thier own perfect which is very subjective. Please ask questions!