In terms of health, you do, of course worry about the physical condition of the puppy--good weight, shiny coat, lots of energy, the proper vet care (shots, worming and so on), but a lot of the health tests you look for should have been done on the parents before they were bred.
$3000-$3500 is what I would expect to pay here on the West Coast from the breeder of our last 3 (soon to be 4) dogs. In the US, a puppy from a recommended breeder of quality Dobermans should come to its new home with cropped ears, a docked tail and its dew claws removed. The pup should recurrent on all shots appropriate to its age.
Dobermans are an expensive breed to own. As a breed, they are prone to certain health issues. As melbrod mentioned, proper health screening of both parents is essential.
If you let folks here know what part of the country you live in, you may get the names of some breeders to reach out to.
The Desert Valley Doberman Pinscher Club is in Arizona, and they are a very, very active club. I would highly recommend reaching out to them - they would be a great resource for you, and would be very helpful in connecting you with breeders in your area.
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That is my best advice for finding people in the area closest to you who would be really connected with the local breeding activity. They actually have a monthly meeting in just three days (virtually, due to Covid) that you could probably sit in on as a guest. They also have a show coming up in March - if it is held, I would HIGHLY recommend going, if they allow visitors/observers. Meeting people in person is such a good way to get to know breeders and see who is a good fit for you.