Greetings and welcome to the forum!
A few "facts of life" regarding Doberman ownership:
Many rental housing units do not permit Dobes, as their insurance company has them black-listed as a "dangerous breed".
Many homeowners insurance companies will cancel a homeowners policy if they have a dog labeled a "dangerous breed". FYI, State Farm has no breed restrictions.
Ethical breeders will be very concerned about selling a pup to someone who may be deployed because it's common for the military person to find out they cannot take the dog with them.
Reputable animal shelters and rescue groups hesitate to place a dog with someone who has an obligation to the military due to the same concern.
Ethical breeders don't breed their dogs frequently. And when they breed their dogs, there is usually a waiting list, (the pups are, essentially, "pre-sold"). So, it's difficult to get a pup from an ethical breeder on short notice.
If you live alone and work full-time, ethical breeders and reputable shelters/rescue will be concerned about all the mischief an unattended pup can get into while you are out. An adult dog may be a better match for your lifestyle.
EDIT: n/m; just saw you share your home with your girlfriend.
Breeders may have a non-pup available for a variety of reasons. It may have been kept back by the breeder to see how it matured. The dog did not mature as the breeder hoped, and now the breeder wants to place the dog into a pet home. Or, the dog was returned to the breeder because the owner could no longer keep it (health crisis, loss of income, death).
Rescue: few rescued Dobes are cropped, and if they are, it's often a botched job. That said, there are two black cropped and docked males at the Amarillo (Texas) animal control facility who, if they are not claimed by the owners or adopted by Februray 13, will be euthanized. Dobe rescue groups are full and no one has room for them. Both boys are said to be about 2-3 years old. I don't know their details but would be happy to put you in touch with someone who can tell you more. Also, transport can be arranged. PM me.:wavey:
ETA: is your resident dog male or female?
ETA2: two Dobe rescue groups in your area:
Las Vegas Doberman and Dachshund Rescue and
Doberman Rescue of Nevada